Determination of Cardiac Parameters for Modulation of Blood Pump Support

ABSTRACT

The systems, devices, and methods presented herein use a blood pump to obtain measurements of cardiac function. The system can quantify the functioning of the native heart by measuring certain parameters/signals such as aortic pressure or motor current, then calculate and display one or more cardiac parameters and heart function parameters, such as left ventricular pressure, left ventricular end diastolic pressure, or cardiac power output. These parameters provide valuable information to a user regarding current cardiac function, as well as positioning and function of the blood pump. In some embodiments, the system can act as a diagnostic and therapeutic tool. Providing cardiac parameters in real-time, along with warnings about adverse effects and recommendations to support cardiac function, such as increasing or decreasing the volumetric flow rate of blood pumped by the device, administering pharmaceutical therapies, and/or repositioning the blood pump allow clinicians to better support and treat cardiovascular disease.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application62/517,668, filed Jun. 9, 2017, titled “Determination of CardiacParameters for Modulation of Blood Pump Support,” and to U.S.Provisional Application 62/635,662, filed Feb. 27, 2018, titled“Determination of Cardiac Parameters for Modulation of Blood PumpSupport,” the contents of each of which are incorporated in theirentirety by reference herein.

BACKGROUND

Intravascular blood pumps provide hemodynamic support and facilitateheart recovery. Intravascular blood pumps are inserted into the heartand supplement cardiac output in parallel with the native heart toprovide supplemental cardiac support to patients with cardiovasculardisease. An example of such a device is the IMPELLA® family of devices(Abiomed, Inc., Danvers Mass.).

Currently, it is difficult for clinicians to directly and quantitativelydetermine the amount of support a device should deliver or when toterminate use of a cardiac assist device. Thus, clinicians tend to relyon qualitative judgments and indirect estimates of cardiac function,such as measuring intracardiac or intravascular pressures using fluidfilled catheters. Traditionally, left-ventricular pressure (LVP) isestimated by measurement of a Pulmonary Arterial Wedge Pressure (PAWP)or Pulmonary Capillary Wedge Pressure (PCWP) in which a pulmonarycatheter including a balloon is inserted into a pulmonary arterialbranch. PAWP and PCWP are not an effective measurement of cardiachealth, as the pulmonary arterial catheters are intermittent, indirect,and inconsistent, resulting in incorrect data which cannot be usedreliably by clinicians to make clinical decisions regarding the level ofcardiac support required by a patient.

Blood pumps provide supplemental cardiac support by assisting in pumpingblood through the chambers of the heart, for example from the leftventricle or atrium into the aorta, and from the right atrium orventricle into the pulmonary artery. Blood pumps are typically insertedto assist with cardiac support for a time period, after which thepatient is weaned from the blood pump support, allowing the heart topump blood unsupported. Because clinicians do not have access toreliable information about cardiac function, patients are often weanedtoo early and too quickly causing unnecessary strain on the heart.

Accurate measurements of left-ventricular pressure, cardiac power outputand other cardiac variables could allow clinicians to make betterclinical decisions for patients based on the current needs of the heart.Accordingly, there is a long-felt need for improvements over the presentday systems providing information about cardiac support and cardiachealth to clinicians.

SUMMARY

In some implementations, a method for providing cardiac support to aheart includes operating a blood pump positioned in the heart, the bloodpump having a cannula, a motor operating at a motor speed and drawing avariable current to provide a level of cardiac support to the heart. Theblood pump also includes a controller coupled to the blood pump. Themethod also includes the controller measuring an aortic pressure,measuring the motor current and the motor speed, determining a pressuregradient across the cannula associated with the motor current and themotor speed, using a processor to calculate a calculated cardiacparameter from the aortic pressure and the pressure gradient across thecannula associated with the motor current and the motor speed, forexample the left-ventricular pressure (LVP) or left-ventricularend-diastolic pressure (LVEDP). The method also includes recording thecalculated cardiac parameter in a memory and using the calculatedcardiac parameter to determine a heart function parameter, for example ameasure of cardiac power output. The method continues by determining arecommended change to the support provided by the blood pump based onthe calculated cardiac parameter and the heart function parameter, andgenerating the recommended change to the support for display. Therecommended change to the support may be, for example, a recommendationfor increasing or decreasing the motor speed during weaning, arecommendation to adjust the positioning of the blood pump in responseto a suction event, or a recommendation to change to a different bloodpump having different capabilities, among other recommendations. Themethod may also include generating for display the calculated cardiacparameters and heart function parameters. Displaying important cardiacparameters and heart function parameters allow health care professionalsto make informed decisions about the modulation of blood pump support topatients. Further, the calculation of these parameters based on themotor current and the motor speed of the blood pump and measured aorticpressure enable the determination of recommendations for modulation andadjustment of the blood pump that can be provided to health careprofessionals to aid in the determination of possible issues and toprompt adjustments in care.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects and advantages will be apparent uponconsideration of the following detailed description, taken inconjunction with the accompanying drawings, in which like referencecharacters refer to like parts throughout, and in which:

FIG. 1 shows an intravascular heart pump system located in a heart;

FIG. 2A shows an example plot of motor current versus a pressuregradient;

FIG. 2B shows an example plot of measured aortic pressure and calculatedLVP as a function of time;

FIG. 2C shows an example plot of the LVP waveform and the aorticpressure waveform as a function of time;

FIG. 2D shows an example plot of the first time-based derivative of theLVP wave form as a function of time;

FIG. 2E shows an example plot of the second time-based derivative of theLVP wave form as a function of time

FIG. 3 shows an exemplary user interface for a heart pump controllerdisplaying measurements over time;

FIG. 4 shows a process for optimizing the performance of a blood pump inthe heart based on measured and calculated cardiac parameters;

FIG. 5A shows an exemplary user interface for a heart pump controllerillustrating an intermittent suction event at the blood pump;

FIG. 5B shows an exemplary user interface for a heart pump controllerillustrating a continuous suction even at the blood pump;

FIG. 5C shows an exemplary user interface for a heart pump controllerillustrating a metric trend screen;

FIG. 5D shows an exemplary user interface for a heart pump controllerillustrating changes in heart function during weaning as captured by thedisplayed metrics;

FIG. 6 shows a process for determining a cardiac power output anddisplaying a recommendation for modulation of pump support to a user;

FIG. 7 shows a process for recommending an adjustment to a motor speedbased on measured and calculated cardiac parameters;

FIG. 8 shows a process for recommending an adjustment to a motor speedbased on a cardiac power output and LVEDP;

FIG. 9 shows a process for recommending a higher flow device fortreatment based on measured and calculated cardiac parameters;

FIG. 10 shows a process for recommending a pharmaceutical therapy basedon measured and calculated cardiac parameters;

FIG. 11 shows a process for alerting a user of predicted adverse cardiacevents based on measured and calculated cardiac parameters; a

FIG. 12 shows a process for balancing right and left-sided blood pumpdevices during bi-ventricular support based on measured and calculatedcardiac parameters;

FIG. 13 shows a process for automatically modifying a level of supportprovided by the blood pump; and

FIG. 14 shows a block diagram of an exemplary blood pump system.

DETAILED DESCRIPTION

To provide an overall understanding of the systems, method, and devicesdescribe herein, certain illustrative embodiments will be described.Although the embodiments and features described herein are specificallydescribed for use in connection with a percutaneous blood pump system,it will be understood that all the components and other featuresoutlined below may be combined with one another in any suitable mannerand may be adapted and applied to other types of cardiac therapy andcardiac assist devices, including cardiac assist devices implanted usinga surgical incision, and the like.

The systems, devices, and methods described herein provide mechanismsfor providing cardiac parameters and heart function parameters toclinicians based on the motor current, the motor speed, and the aorticpressure measured at a blood pump system. The functionality and outputof the intravascular blood pump, along with measurable cardiacparameters, can be used to calculate additional parameters useful indetermining patient cardiac performance and health. By making thesedeterminations and displaying the data to a clinician in a useful andmeaningful way, the clinician has more data available to informhealthcare decisions. The additional cardiac parameters and heartfunctions, as well as trends in the same, accessible by algorithms basedon the intravascular blood pump output, allow clinicians to makeinformed decisions regarding cardiac support provided to patients byvarious blood pumps, by the positioning of the blood pumps, and byadministration of pharmaceutical therapeutics. The algorithms also allowthe blood pump system to determine important cardiac parameters anddisplay them to clinicians to inform patient care decisions, or to makerecommendations for modulation of support, for example by displaying arecommendation of varying levels of heart function to a clinician basedon a variety of cardiac parameter inputs.

The calculation of various cardiac parameters from the blood pumpfunction is possible based on knowledge of the blood pump operation, forexample knowledge of the pressure and flow responses of the heart withregard to the blood pump operational speed and input power. Based on theoperational functionality of the pump within the heart, algorithms canbe constructed that calculate how cardiac metrics vary as the blood pumpinteracts with the cardiac system. By making these determinations andproviding clinicians with immediate and historical cardiac parameters,clinicians are better able to understand and react to changes in bloodpump functionality or patient cardiac health.

In particular, providing clinicians with accurate and timely cardiacparameters, such as LVEDP, LVP, aortic pulse pressure, mean aorticpressure, pump flow, pressure gradient, heart rate, cardiac output,cardiac power output, native cardiac output, native cardiac poweroutput, cardiac contractility, cardiac relaxation, fluid responsiveness,volume status, cardiac unloading index, cardiac recovery index,left-ventricular diastolic function, left-ventricular diastolicelastance, left-ventricular systolic elastance, stroke volume, heartrate variability, stroke volume variability, pulse pressure variability,aortic compliance, vascular compliance, or vascular resistance, enablesthe clinicians to make well-informed decisions about patient care. Bothtotal and native cardiac outputs can be determined using the methods andsystems described herein. The native cardiac output is used herein todescribe a cardiac output of the heart alone, without the contributionof a blood pump. Similarly, the native cardiac power output is used todescribe the cardiac power output of the heart without any contributionof the blood pump. The total cardiac output, in contrast, is used hereinto describe the cardiac output produced by the combination of the heartand the blood pump. Similarly, the total cardiac power output is used todescribe the cardiac power output of the heart including both the nativepower output contribution of the heart and the blood pump. Throughoutthis application, when cardiac power output or cardiac output isdetermined or calculated, the systems and methods described herein arecapable of calculating either the total or the native cardiac output,and reference to cardiac output or cardiac power output may refer toeither of native or total outputs.

The algorithms discussed herein enable clinicians to make informeddecisions about the weaning of patients. A clinician can betterdetermine the appropriate timing for weaning a patient from blood pumpprovided cardiac support based on the provided parameters. Further, thealgorithms provided herein can enable clinicians to make decisions aboutthe proper rate at which to wean a patient by providing recommendationsabout the level of support, motor speed, and appropriate blood pumps toprovide the recommended motor speed to support the cardiac function.

The systems, devices, and methods described herein further aid in theoptimization of the performance of the blood pump by the measurement andcalculation of cardiac parameters. Estimations of LVP and real-timedisplay of the LVP waveform, along with other cardiac metrics, enable aphysician to understand the currently and historical cardiac function ofa patient, and well as the level of support being provided by the bloodpump. Using this information, physicians make determinations regardingmodifications to the level of support being provided (for example,weaning a patient from support or increasing provided support),positioning and functionality of a blood pump, the occurrence of suctionevents, and other clinical determinations as described below.

The systems, devices, and methods described herein enable a clinician tovisually determine whether the blood pump is properly positioned in theheart and functioning appropriately. The LVP estimate is very sensitiveto suction events and can be employed to inform clinicians about suctionevents and improper positioning, and to aid in re-positioning of thepump in the heart. The cardiac metrics determined according to thealgorithms described herein and displayed to clinicians can further aidin identifying the cause of suction events when they occur.

Additionally, the systems, devices, and methods described herein provideclinicians with data and recommendations to provide additionaltherapeutic support, such as the administration of pharmaceuticaltherapies to a patient to aid in the recovery of cardiac function. Forexample, based on cardiac parameters and trends in the parameters, thealgorithms can provide recommendations as to which pharmaceuticaltherapies can be beneficial as well as provide dosing information. Aclinician may be provided with trends in the cardiac parameters such asthe native cardiac output, the end-diastolic pressure, and the cardiacpower output, and based on the trends, the algorithms may makerecommendations in support of the titration of inotropes.

Alternatively, a clinician may be presented with cardiac parameters toaid in the modulation of fluids and the volume status of the patient.The clinician may be provided with the native output, the end-diastolicpressure, and pulse pressure variation to enable the clinician todetermine whether the patient is in an optimum fluid window, and thefluid responsiveness of the patient. The algorithm may provide anotification to the clinician indicating, based on these parameters,whether the patient is considered to be in an optimum fluid window andan indication of whether the patient is likely to be responsive to theadministration of fluids.

The systems, devices, and methods described herein can be used toprovide a warning to clinicians regarding predicted adverse events thatare predicted based on measured and calculated cardiac parameters.Patients reliant on blood pump support are at risk for additionalischemic events. Small changes in the left-ventricular contractility,left-ventricular relaxation, and LVEDP are all early indicators of asilent ischemic event. Alerting a clinician about changes in theseparameters enables clinicians to detect ischemic events earlier and torespond more quickly. Additionally, other adverse events and outcomessuch as aortic regurgitation and conduction abnormalities (in the caseof patients undergoing balloon aortic valvuloplasty (BAV) in preparationfor a trans-catheter aortic valve replacement (TAVR)) requiring apacemaker. Changes in left-ventricular relaxation, left-ventriculardiastolic filling pressure, systolic pressure gradients, and cardiacpower and total power can all function as early indicators of such anevent, and may be calculated and detected by the algorithms describedherein and presented to clinicians.

Finally, the systems, devices, and methods described herein can be usedto balance a right-sided and left-sided device used simultaneously, forexample providing bi-ventricular support, the balancing of the twodevices can present a unique challenge of balancing the right andleft-side devices to maintain appropriate pressures in the lungs andlimit the risk of pulmonary edema. By measuring the native and totaloutputs along with the pulmonary artery pressure and theleft-ventricular diastolic pressure, the algorithm can provideclinicians with information about these parameters to help informdecisions about the operation of the bi-ventricular devices and canprovide recommendations to help the clinicians to balance the twodevices.

The systems, devices, and methods presented herein describe a mechanismof measuring, in a blood pump system, based on the output of the bloodpump and measured pressure signal, a variety of cardiac parameters andheart function parameters that are useful to clinicians in the care andtreatment of patients being treated with cardiac support by a bloodpump. The parameters and recommendations provided by the algorithm maybe used by clinicians to inform a variety of medical treatmentdecisions, as described below.

FIG. 1 shows an exemplary prior art cardiac assist device located in aheart 102. The heart 102 includes a left ventricle 103, aorta 104, andaortic valve 105. The intravascular heart pump system includes acatheter 106, a motor 108, a pump outlet 110, a cannula 111, a pumpinlet 114, and a pressure sensor 112. The motor 108 is coupled at itsproximal end to the catheter 106 and at its distal end to the cannula111. The motor 108 also drives a rotor (not visible in figure) whichrotates to pump blood from the pump inlet 114 through the cannula 111 tothe pump outlet 110. The cannula 111 is positioned across the aorticvalve 105 such that the pump inlet 114 is located within the leftventricle 103 and the pump outlet 110 is located within the aorta 104.This configuration allows the intravascular heart pump system 100 topump blood from the left ventricle 103 into the aorta 104 to supportcardiac output.

The intravascular heart pump system 100 pumps blood from the leftventricle into the aorta in parallel with the native cardiac output ofthe heart 102. The blood flow through a healthy heart is typically about5 liters/minute, and the blood flow through the intravascular heart pumpsystem 100 can be a similar or different flow rate. For example, theflow rate through the intravascular heart pump system 100 can be 0.5liters/minute, 1 liter/minute, 1.5 liters per minute, 2 liters/minute,2.5 liters/minute, 3 liters/minute, 3.5 liters/minute, 4 liters/minute,4.5 liters/minute, 5 liters/minute, greater than 5 liters/minute or anyother suitable flow rate.

The motor 108 of the intravascular heart pump system 100 can vary in anynumber of ways. For example, the motor 108 can be an electric motor. Themotor 108 can be operated at a constant rotational velocity to pumpblood from the left ventricle 103 to the aorta 104. Operating the motor108 at a constant velocity generally requires supplying the motor 108with varying amounts of current because the load on the motor 108 variesduring the different stages of the cardiac cycle of the heart 102. Forexample, when the mass flow rate of blood through the blood pump intothe aorta 104 increases (e.g., during systole), the current required tooperate the motor 108 increases. This change in motor current can thusbe used to help characterize cardiac function as will be discussedfurther in relation to the following figures. Detection of mass flowrate using motor current may be facilitated by the position of the motor108, which is aligned with the natural direction of blood flow from theleft ventricle 103 into the aorta 104. Detection of mass flow rate usingmotor current may also be facilitated by the small size and/or lowtorque of the motor 108. The motor 108 of FIG. 1 has a diameter of about4 mm, but any suitable motor diameter may be used provided that therotor-motor mass is small enough, has low enough torque, and ispositioned such that it is able to quickly and easily respond to changesin the physiologic pressure gradient across the pump. In someimplementations, the diameter of the motor 108 is less than 4 mm.

In certain implementations, one or more motor parameters other thancurrent, such as power delivered to the motor 108, are measured. In someimplementations, the motor 108 in FIG. 1 operates at a constantvelocity. In certain implementations the speed of the motor 108 isvaried over time (e.g., as a delta, step, sinusoid, or ramp function) toprobe the native heart function. In some implementations, the motor 108may be external to the patient and may drive the rotor by an elongatemechanical transmission element, such as a flexible drive shaft, drivecable, or a fluidic coupling.

The pressure sensor 112 of the intravascular heart pump system 100 canbe disposed at various locations on the pump, such as on the motor 108or at the outflow of the pump, i.e. pump outlet 110. Placement of thepressure sensor 112 at the pump outlet 110 enables the pressure sensor112 to measure the true aortic pressure (AoP), when the intravascularblood pump system 100 is positioned across the aortic valve 105. Incertain implementations, the pressure sensor 112 of the intravascularheart pump system 100 can be disposed on the cannula 111, on thecatheter 106, or in any other suitable location. The pressure sensor 112can detect blood pressure in the aorta 104 when the intravascular heartpump system 100 is properly positioned in the heart 102. The bloodpressure information can be used to properly place the intravascularheart pump system 100 in the heart 102. For example, the pressure sensor112 can be used to detect whether the pump outlet has passed through theaortic valve 105 into the left ventricle 103 which would only circulateblood within the left ventricle 103 rather than transport blood from theleft ventricle 103 to the aorta 104. In some implementations, thepressure sensor 112 is a fluid filled tube, a differential pressuresensor, hydraulic sensor, piezo-resistive strain gauge, opticalinterferometry sensor or other optical sensor, MEMS piezo-electricsensor, or any other suitable sensor.

The intravascular heart pump system 100 can be inserted in various ways,such as by percutaneous insertion into the heart 102. For example, theintravascular heart pump system can be inserted through a femoral artery(not shown), through the aorta 104, across the aortic valve 105, andinto the left ventricle 103. In certain implementations, theintravascular heart pump system 100 is surgically inserted into theheart 102. In some implementations, the intravascular heart pump system100, or a similar system adapted for the right heart, is inserted intothe right heart. For example, a right heart pump similar to theintravascular heart pump system 100 can be inserted through the femoralvein and into the inferior vena cava, bypassing the right atrium andright ventricle, and extending into the pulmonary artery. Alternatively,a right heart pump can be inserted through the internal jugular vein andsuperior vena cava, and a left heart pump can be inserted through theaxillary artery. In certain implementations, the intravascular heartpump system 100 may be positioned for operation in the vascular systemoutside of the heart 102 (e.g., in the aorta 104). By residing minimallyinvasively within the vascular system, the intravascular heart pumpsystem 100 is sufficiently sensitive to allow characterization of nativecardiac function.

FIG. 2A shows an example plot of motor current versus a pressuregradient. The plot 200 has an x-axis 202 representing motor current inunits of mA and a y-axis 204 representing a pressure gradient (dP) inunits of mmHg. The plot 200 includes trend line 206 showing arelationship between the motor current and the pressure gradient. Themotor current drawn by a blood pump is proportional to the pressuregradient across the blood pump cannula at a known motor speed. The plot200 may function as a look-up for an algorithm to determine a pressuregradient from a given motor current and motor speed at which a bloodpump motor is currently operating. For example, a motor current of about650 mA indicated by point 208 on the x-axis corresponds to a pressuregradient of 120 mmHg indicated by point 210 on the y-axis, determined byextending a line up from the motor current at point 208 to the trendline 206, and then extending a line from the intersection with the trendline 206 to the y-axis at point 210. The relationship between the motorcurrent and pressure gradient described by plot 200 may be determined ina lab for a particular blood pump under physiological conditions and maybe stored in a memory of a processor within a blood pump controller.

By accessing the plot 200, a controller determines the pressure gradientassociated with a motor current and motor speed at which the blood pumpis currently operating. The controller can then use the pressuregradient with other determined or measured values such as the aorticpressure measured at a pressure sensor (for example, pressure sensor 112in FIG. 1) to determine various cardiac parameters such as LVEDP, LVP,aortic pulse pressure, mean aortic pressure, pump flow, pressuregradient, heart rate, cardiac output, cardiac power output, nativecardiac output, native cardiac power output, cardiac contractility,cardiac relaxation, fluid responsiveness, volume status, cardiacunloading index, and cardiac recovery index.

For example, once the pressure gradient across the blood pump cannulahas been determined from the motor current and motor speed, the pressuregradient across the blood pump cannula can be used with a measuredaortic pressure (such as pressure measured at the pressure sensor 112)to determine an estimation of the LVP at the inlet cage of the pump. TheLVP is estimated by subtracting the pressure gradient from the aorticpressure. As described below with regard to FIG. 2B, the LVP determinedin this way is a very good estimate of the actual LVP in the heart. Theestimated LVP can be displayed, by the controller, on a display screenwhere it can be accessed and viewed by a clinician. The clinician canuse the information provided by the LVP at a given moment, or ahistorical view of changes to the LVP, to make clinical decisionsregarding the treatment of a patient including making informed decisionsabout changes to the support provided by the blood pump.

Although the relationship between the pressure gradient and the motorcurrent of the blood pump at a known motor speed is depicted as a plot200, a controller could use the information contained in the plot 200 byaccessing a look-up table, or by querying a function describing therelationship between the pressure gradient and the motor current andmotor speed. In some implementations, the controller may take intoaccount additional parameters beyond the motor current and motor speedin determining the pressure gradient across the blood pump cannula, suchas other properties of the pump, properties of the pump controller orconsole, environmental parameters, and motor speed settings. Accountingfor additional parameters in the function used to determine the pressuregradient may lead to an association between the motor current andpressure differential that is more accurate, allowing for a moreaccurate calculation of the LVP or other cardiac parameters.

FIG. 2B shows an example plot of measured aortic pressure and calculatedLVP as a function of time. The plot 201 has an x-axis 203 representingtime in seconds and a y-axis 205 representing a pressure head in unitsof mmHg. The plot has three traces including the aortic pressure 212,the estimated LVP 214 (dotted line), and the actual measured LVP 216.The traces on the plot 201 illustrate that the estimated LVP determinedfrom the measured aortic pressure and the determined pressure gradientacross the blood pump cannula is in agreement with the measured LVPvalue. Based on the motor current and the measured aortic pressure, thealgorithm determines continuous LVP including the full-waveform andLVEDP point within the cardiac cycle. The algorithm measures the LVPimmediately inside the pump inlet 114, enabling the algorithm todetermine suction events and to distinguish between systolic/continuousand diastolic/intermittent suction.

The LVEDP point in the cardiac cycle is important in the calculation ofother cardiac parameters. The pressure at the end-diastole point is theLVP immediately prior to left-ventricular contraction, which can bedefined by the onset of the R-wave in a reference EKG measurement. TheLVEDP point in the cardiac cycle can be estimated based on the aorticpressure 212 placement signal, LVP 214 waveform and the pressuregradient at the pump. In some implementations, the LVEDP is estimatedbased on the identification of a peak in estimated LVP 214 waveform thatis then shifted on the time axis to estimate the LVEDP point. Thistechnique is referred to as peak detection and time indexing. In analternative implementation, the estimated LVEDP is calculated based on afirst and/or second time-based derivative of the estimated LVP 214waveform over time.

FIG. 2C shows an example plot 220 of the estimated LVP 214 waveform andthe aortic pressure 212 waveform with respect to time. The plot has anx-axis 222 representing time and a y-axis 224 representing pressure headin mmHg. The plot includes a trace of the estimated LVP waveform 226(dotted line) and a trace of the aortic pressure 228 (solid line). Insome implementations, the LVEDP can be selected based on the plot 220 byselecting a peak of the estimated LVP waveform 226 and shifting thepoint in time. Though only one LVEDP point 229 is shown in this plot 220for convenience, the LVEDP may be calculated for each cycle of the LVPwaveform to monitor changes over time.

FIG. 2D shows an example plot 230 of the first derivative of theestimated LVP 214 waveform with respect to time. The plot 230 can becalculated as a derivative of the LVP waveform 226 in plot 220. The plot230 has an x-axis 232 representing time and a y-axis 234 representing afirst derivative of pressure with respect to time (dP/dt) in mmHg/sec.The plot includes a trace of the first derivative of the LVP waveform236, as well as an indication of the LVEDP point 238 which may beselected as the estimated LVEDP based on the trace of the firstderivative of the LVP waveform 236. The point 238 shows the pointassociated with the LVEDP, which may be calculated, for example, as thepoint at which the first derivative of the LVP waveform 236 is at a timepoint halfway between a minimum valley and maximum peak. Though only oneLVEDP point 238 is shown in this plot 230 for convenience, the LVEDP maybe calculated for each cycle of the LVP waveform. Alternatively, theplot 230 of the first derivative of the LVP waveform 236 can be usefulin “windowing” or narrowing a search for the LVEDP point 238 which maythen be determined based on the second derivative plot or other means.The estimation of the LVEDP point 238 based on the plot 230 can besensitive to sampling frequency with higher sampling frequency, suchthat higher sampling results in a more accurate calculation of the LVEDPpoint 238.

FIG. 2E shows an example plot 240 of the second derivative of theestimated LVP 214 waveform with respect to time. The plot 230 can becalculated as the derivative of the LVP waveform 236 in plot 230, or thesecond derivative of the LVP waveform 226 in plot 220. The plot 240 hasan x-axis 242 representing time and a y-axis 244 representing the secondderivative of pressure with respect to time (d²P/dt²) in mmHg/sec². Theplot includes a trace of the second derivative of the LVP waveform 246,as well as an indication of the LVEDP point 248 which may be selected asthe estimated LVEDP based on the trace of the second derivative of theLVP waveform 246. The point 248 shows the point associated with theLVEDP, which may be calculated, for example, as the point at which thesecond derivative of the estimated LVP waveform 246 has a maximum peak.Though only one LVEDP point 248 is shown in this plot 240 forconvenience, the LVEDP may be calculated for each cycle of the LVPwaveform. Similar to the estimation of LVEDP point 238 based on thefirst derivative plot 230, the estimation of the LVEDP point 248 basedon the second derivative plot 240 can be sensitive to sampling frequencyand is more accurate at high sampling frequencies.

The peaks of the first or second time-derivative of the LVP waveform canbe used to accurately calculate the LVEDP point. Further, the peaks andvalleys of the first and second time-derivatives of the LVP waveform canbe used to narrow the search window for a given LVEDP point and thusimprove detection of the LVEDP point, reducing false positives. Usingthe first or second time-based derivative of the measured aorticpressure 212 to determine the LVEDP enables the algorithm to moreaccurately determine the LVEDP point in the cardiac cycle.Alternatively, the aortic pressure waveform (e.g., 212 in FIG. 2B) canbe similarly used with first and second derivatives of the aorticpressure waveforms to determine the LVEDP point.

FIG. 3 shows an exemplary user interface for a heart pump controllerdisplaying a waveform of cardiac function over time. The user interface300 may be used to control the intravascular heart pump system 100 ofFIG. 1, or any other suitable heart pump. The user interface 300includes a pressure signal waveform 302, an LVP waveform 303, and amotor current waveform 304, a flow rate 306, a measure of cardiac poweroutput 308, and a measure of native cardiac output 310. The pressuresignal waveform 302 indicates the pressure measured by the blood pump'spressure sensor (e.g., pressure sensor 112) and, when the pump isproperly placed, corresponds to an aortic pressure. The pressure signalwaveform 302 and the LVP waveform 303 can be used by a healthcareprofessional to properly place an intravascular heart pump (such asintravascular heart pump 100 in FIG. 1) in the heart. The pressuresignal waveform 302 is used to verify the position of the intravascularheart pump by evaluating whether the waveform 302 is an aortic orventricular waveform. An aortic waveform indicates that theintravascular heart pump motor is in the aorta. A ventricular waveformindicates that the intravascular heart pump motor has been inserted intoan incorrect location in the ventricle. A scale 312 for the placementsignal waveform is displayed to the left of the waveform. The defaultscaling is 0-160 mmHg. It can be adjusted in 20 mmHg increments, forexample, the scale 312 is shown with scaling from −20-160 mmHg. To theright of the waveform is a display 314 that labels the waveform,provides the units of measurement, and includes an indication of thecurrent estimated pressure. The display 314 may also include anestimation of aortic pressure 316 and/or LVP 318, which may be aninstantaneous estimation, average value, or a maximum or minimum value,as well as indications of other cardiac parameters calculated from thepressure signal waveform, such as the LVEDP. In some implementations,the display 314 shows the maximum and minimum values and the averagevalue from the calculated cardiac metrics. By including the pressuresignal waveform 302, the LVP waveform 303, and the display 314, thepressure signal and LVP are displayed as a function of time andimportant cardiac parameters are extracted and displayed in the display314.

In some implementations, a variability between different blood pumps isaccounted for by calibrating the LVP waveform 303 to the measured aorticpressure waveform 302. The user may be prompted by the display tomanually adjust the estimated LVP waveform peak (e.g., 214 in FIG. 2B)along the y-axis to coincide with the aortic pressure waveform peak(e.g., 212 in FIG. 2B). In some implementations, the calibration isautomated for the user based on the pressure reading of the aorticpressure and the LVP waveforms. In other implementations, the requiredcalibration may be calculated by a controller in the user interface 300,and a prompt with instructions to align the LVP waveform peaks duringsystole to the same peaks in the aortic pressure waveform may bepresented to the user including a suggested value based on thecontroller's calculation of the same alignment in the background of theprogram. By calculating the alignment in the background, the controllercan also detect the exact points in the cardiac cycle where the aorticpressure waveform and the LVP waveform should overlap. The overlap ofthe aortic pressure waveform and the LVP waveform corresponds to theaortic valve opening and aortic valve closing. These events mark thebeginning and end of systole. Determination the points of overlapbetween the aortic pressure waveform and LVP waveform is difficult byeye, but can be calibrated by the controller to improve overcalibrations that require identification of peaks of the LVP and aorticpressure waveforms.

Automating the calibration procedure simplifies the use of the userinterface 300 and ensures appropriate calibration values are presentedto the user. The calibration calculations can be further improved athigh sampling frequencies.

The motor current waveform 304 is a measure of the energy intake of theheart pump's motor. The energy intake varies with the motor speed andthe pressure difference between the inlet and outlet areas of thecannula resulting in a variable volume load on the rotor. When used withan intravascular heart pump (such as intravascular heart pump 100 inFIG. 1), the motor current provides information about the catheterposition relative to the aortic valve. When the intravascular heart pumpis positioned correctly, with the inlet area in the ventricle and theoutlet area in the aorta, the motor current is pulsatile because themass flow rate through the heart pump changes with the cardiac cycle.When the inlet and outlet areas are on the same side of the aorticvalve, the motor current will be dampened or flat because the inlet andoutlet of the pump are located in the same chamber and there is novariability in differential pressure resulting in a constant mass flowrate, and subsequently constant motor current. A scale 320 for the motorcurrent waveform is displayed to the left of the waveform. The defaultscaling is 0-1000 mA. The scaling may be adjustable in 100 mAincrements. To the right of the waveform is a display 322 that labelsthe waveform, provides the units of measurement, and shows the maximumand minimum values and the average value from the samples received.Though the pressure sensor and motor current sensor may not be requiredfor positioning of surgically implanted pumps the sensors can be used insuch devices to determine additional characteristics of native heartfunction to monitor therapy.

While only the three waveforms are shown in FIG. 3 (pressure signalwaveform 302, LVP waveform 303, and the motor current waveform 304)additional waveforms may be displayed on the main screen of the display300 or accessible on additional screens. For example, a contractilitywaveform, a cardiac state waveform, an ECG waveform, or any otherappropriate cardiac parameter which changes with time or pulse can bedisplayed on display 300. The display of cardiac information as a trendline allows a physician to view the historical cardiac state of apatient and to make decisions based on the visible trends. For example,a physician may observe a decline or increase in the aortic pressuredisplayed in the pressure signal waveform 302 over time and determine toalter or continue treatment based on this observation.

The position, depictions of the metrics on the controller, and theidentification and number of metrics and recommendations in FIG. 3 aremeant to be illustrative. The number of metrics and indicators, positionof same metrics and indicators on the console and the metrics displayedmay be varied from those shown here. The cardiac parameters displayed toa user can be, for example, LVEDP, LVP, aortic pulse pressure, meanaortic pressure, pump flow, pressure gradient, heart rate, cardiacoutput, cardiac power output, native cardiac output, native cardiacpower output, cardiac contractility, cardiac relaxation, fluidresponsiveness, volume status, cardiac unloading index, cardiac recoveryindex, left-ventricular diastolic function, left-ventricular diastolicelastance, left-ventricular systolic elastance, stroke volume, heartrate variability, stroke volume variability, pulse pressure variability,aortic compliance, vascular compliance, or vascular resistance. In someimplementations, the font, font size, layout, and positioning of thedata displayed to a user may be configured for ease of use in a criticalcare setting.

The measure of the measure of native cardiac output 310 includes adisplay of a NCO in L/min calculated based on the measured cardiacparameters. The native cardiac output is a measure of the blood flowattributed to the heart itself, or the rate of blood flow in thevasculature surrounding the blood pump. The native cardiac output iscalculated from the placement signal (Aortic Pressure) 316 and the pulsepressure calculated at the controller by subtracting the minimum aorticpressure value from the maximum aortic pressure value. The pulsepressure may be calculated by the controller periodically. The nativecardiac output can be used to calculate additional cardiac parameters ofclinical relevance. For example, the native cardiac output can be usedin conjunction with information about the flow rate of the blood pump tocalculate a total cardiac output of the heart itself and the blood pump.

The measure of cardiac power output 308 includes a display of a totalcardiac power output in Watts calculated based on the measured cardiacparameters. The total cardiac power output is calculated from the totalcardiac output, calculated based on the native cardiac output asdescribed above. The total cardiac power output is calculated bymultiplying the cardiac output by the mean arterial pressure anddividing by 451.

The flow rate 324 can be a target blood flow rate set by the user or anestimated actual flow rate. In some modes of the controller, thecontroller will automatically adjust the motor speed in response tochanges in afterload to maintain a target flow rate. In someimplementations, if flow calculation is not possible, the controllerwill allow a user to set a fixed motor speed indicated by speedindicator.

A memory within the user interface or controller records the datameasured, calculated and displayed on the controller. The memory mayhave a sampling rate of 25-150 Hz. In some implementations, a highersampling rate, such as 100 Hz or greater, is preferable as the data willbe recorded in a data log in the memory at a faster rate. The higherfidelity data recorded in the memory can be used to better estimatecardiac function over time. The waveforms, algorithms, and alarmsdisplayed to the user on the user interface may be displayed at a lowerrate for efficiency.

The display 300 includes various buttons 326-334 to access additionaldisplay screens. The buttons include a menu button 326, purge menubutton 328, display button 330, flow control button 332, and mute alarmbutton 334. The buttons shown on display 300 are meant to beillustrative, and alternate or additional buttons may be accessible to auser. The menu button 326 may allow a user to access additionalinformation about the use of the display 300, including softwareversion, registrations, and dates of use. The menu button 326 may alsoallow a user to access options such as the power mode of the display 300or locking the display 300. The menu button 326 may also allow a user tocalibrate the display 300 or allow a user to access options orinstructions for the calibration of the display 300 in conjunction withan attached blood pump. For example, a user may calibrate a measuredpressure value or a cardiac parameter displayed as a waveform to a knownvalue of the cardiac parameter measured by an arterial catheter orsimilar. The purge menu button 328 may allow a user to access additionaluse options, settings, and information related to the purge system of anattached blood pump. The display menu button 330 may allow a user toaccess additional cardiac metrics and parameters and in some cases toadd or change the cardiac metrics displayed on the main screen of thedisplay 300. The flow control button 332 allows a user to accessadditional options and settings related to controlling the flow rate ofthe pump by adjusting the pump motor speed. The flow control button mayallow the user to access recommendations related to the current pumpmotor speed and various cardiac metrics calculated by the controller andmay allow a user to input or accept adjustments to the pump motor speed.The mute alarm button 334 may allow a user to silence an alarm or toaccess additional information about an alarm or warning given by thecontroller. The controller may issue warning notifications to a userregarding the use of the display, blood pump and related systems, or thecardiac metrics calculated by the controller. The warnings and alarmsmay be audible alarms, pop-up screens on the display 300, or may be sentdirectly to a clinician, for example through a text, page, or email.

In some implementations, the warnings or alarms are triggered by acardiac metric calculated, measured or monitored by the controllerfalling below a set threshold value. In some implementations, thewarnings or alarms are triggered by a cardiac metric calculated,measured or monitored by the controller exceeding a set threshold value.In some implementations, the warnings or alarms are triggered by achange in a cardiac metric calculated, measured or monitored by thecontroller exceeding or falling below a set threshold value. In someimplementations, the set threshold value is a system value set withinthe controller. In some implementations, the set threshold value is setby a clinician based on a patient's history and health. In someimplementations, the set threshold value is a previous value of thecardiac metric, for example, a previous value measured or calculated apredetermined amount of time before.

In some implementations, the warnings or alarms are recommendations foraltering the support provided to the heart by the blood pump based onone or more of the calculated, measured, or monitored cardiac metrics.FIGS. 4-11 illustrate processes by which the controller determinesvarious recommended changes to the cardiac support provided by the bloodpump.

FIG. 4 shows a process 400 for optimizing the performance of a bloodpump in the heart based on measured and calculated cardiac parameters.

In step 402, the motor of a heart pump is operated at a rotationalspeed. In step 404, the aortic pressure is measured. The aortic pressuremay be measured by a pressure sensor coupled to the heart pump, by aseparate catheter, by a noninvasive pressure sensor, or by any othersuitable sensor. The pressure sensor may be a fluid-filled tube, adifferential pressure sensor, hydraulic sensor, piezo-resistive straingauge, optical interferometry sensor or other optical sensor, MEMSpiezo-electric sensor, or any other suitable sensor. In someimplementations, ventricular pressure is measured in addition to or inalternative to measuring aortic pressure. In step 406, the currentdelivered to the motor is measured and the motor speed is measured. Instep 408, the pressure differential across a cannula of the blood pumpis determined based on the measured motor current and the motor speed,by using a lookup table or accessing a function that accounts for themeasured motor current at the known speed, and optionally otherparameters. In step 410, a cardiac parameter is calculated based on thepressure differential across the cannula of the blood pump and theaortic pressure. The cardiac parameter may be one of a LVEDP, LVP,aortic pulse pressure, mean aortic pressure, pump flow, pressuregradient, or heart rate. These cardiac parameters can each be used byclinicians as a measure of various aspects of cardiac health andfunction. The trends of each of the cardiac parameters over time can beused by a clinician to determine if the native heart output is improvingor declining and can make clinical decisions about the support beingprovided by the blood pump and pharmaceutical therapies based on thesetrends. In some implementations, more than one cardiac parameter iscalculated based on the pressure differential across the cannula of theblood pump and the aortic pressure.

In particular, in order to evaluate the performance of the blood pumpwithin the heart of a patient, one or more of the LVP and LVEDP may becalculated according to the algorithm. In some implementations, thecalculated metrics are evaluated by the processor to determine whetherthere are problems with a current performance of the blood pump and tooffer suggestions to the user to correct the problems. In someimplementations, the metrics are presented for evaluation by a healthcare professional.

In step 412, the calculated cardiac parameter is recorded in the memory.By accessing the recorded cardiac parameters stored in the memory, ahistorical view of the cardiac parameter over time can be accessed by auser or displayed on a display console as a trend line.

In step 414, a heart function parameter is determined based on thecalculated cardiac parameter. The heart function parameter can be any ofcardiac output, cardiac power output, native cardiac output, nativecardiac power output, cardiac contractility, cardiac relaxation, fluidresponsiveness, volume status, cardiac unloading index, cardiac recoveryindex, left-ventricular diastolic function, left-ventricular diastolicelastance, left-ventricular systolic elastance, stroke volume, heartrate variability, stroke volume variability, pulse pressure variability,aortic compliance, vascular compliance, or vascular resistance. Theseheart function parameters can be calculated from the calculated cardiacparameter and other available measured parameters. The heart functionparameters offer additional information to clinicians about the heartfunction, as well as the performance of the blood pump in relation tothe cardiac function. In some implementations, the heart functionparameter is also recorded in the memory in order to provide historicaldata and heart function parameter trends with respect to time. In someimplementations, more than one heart function parameter is determined.

For example, cardiac output may be calculated based on the motor currentand motor speed of the blood pump and the measured aortic pressure. Fromthe aortic pressure, the pulse pressure of the aortic waveform can bederived. In implementations in which the pressure sensor (e.g., pressuresensor 112 in FIG. 1) is located at the pump outflow, the aorticpressure, and the pulse pressure of the aortic waveform, is measured atthe aortic root where it is less influenced by aortic and systemicresistance and systemic vascular compliance as compared to peripheralapproaches to calculate the pulse pressure (for example, PiCCO, EdwardsFloTract). In some implementations, the pulse pressure, and accordinglythe algorithm calculation, is influenced by the aortic compliance at thepoint of measurement, which varies from patient to patient. However, thepatient-to-patient variance can be accounted for by calibrating thecardiac output algorithm, and the aortic compliance should onlyminimally vary within a patient over the duration of support, as aorticroot wall properties are not typically impacted by vasoactive andinotropic drugs. Other cardiac output algorithms which rely on pulsepressure and derivative of the pulse pressure wave (e.g., PiCCO,FloTract, or PulseCo) cannot discern the pulsatility due to the nativeheart from the pulsatility due to the support device. In contrast, thealgorithm is able to discern native and pump-driven pulsatility andde-couple changes in pulsatility due to changes in flow from either thepump or the heart.

In step 416, the calculated cardiac parameter and/or the heart functionparameter is generated for display and is displayed to a user on adisplay interface. The calculated cardiac parameter can be accessed inthe memory of the controller and processed to ready the cardiacparameter for display as a number, a waveform over time, or as a maximumor minimum value. The cardiac parameter and heart function parameter canbe displayed to a clinician, for example a lab technician or nurse in anintensive care setting or a catheterization lab, on a display, such asdisplay 300 in FIG. 3. The calculated cardiac parameter, the heartfunction parameter, and optionally the historical views of the cardiacparameter and/or heart function parameter over time, allows a clinicianto view and make decisions based on the trends of the cardiac parameterand heart function parameter. An example of user interface is shown inFIG. 5 to illustrate the use of the algorithms derived by the algorithmin determining a correct position of the blood pump.

The display and/or the determination of the cardiac parameter and heartfunction parameter can be continuous or nearly continuous while theheart pump is implanted in the heart. This can be advantageous overconventional catheter-based methods that only allow sampling of cardiacfunction at specific times during the cardiac cycle or at discretepoints in time. For example, continuous monitoring of the cardiacparameter may allow more rapid detection of cardiac deterioration.Continuous monitoring of the cardiac parameter and heart functionparameter can illustrate changes in the heart condition over time.Additionally, if the cardiac assist device is already in the patient,the cardiac function can be measured without having to introduce anadditional catheter into a patient. The cardiac parameter and/or heartfunction parameter may be displayed as shown in the user interface ofFIG. 3 or using any other suitable user interface or report.

In step 418, an optimization of the blood pump performance is determinedbased on the calculated cardiac parameter and heart function parameter.The controller may access the calculated cardiac parameter in the memoryand compare the calculated cardiac parameter or the heart functionparameter to a stored threshold value in order to determine the bloodpump performance can be optimized with regard to the cardiac function ofthe patient. For example, the controller may determine that the patientcardiac function is improving, and the patient can be weaned from bloodpump support. Alternatively, the controller can determine that thepatient cardiac function is declining and the blood pump supportprovided to the patient should be increased. Additionally oralternatively, the controller can determine that there is a suction riskor a suction event based on current placement of the blood pump, andthat the position of the blood pump can be optimized. The thresholdvalue to which the calculated cardiac parameter or heart functionparameter is compared may be pre-set at manufacture, set by thephysician via the user interface, or be based on a previous reading ofthe calculated cardiac parameter and heart function parameter of thepatient. For example, the controller may compare a calculated LVP to athreshold value to determine that there is a suction risk due to currentpositioning of the blood pump. In some implementations, the controllercompares a LVP waveform to one or more a stored waveforms. In someimplementations, the controller compares minimum and/or maximum pointsfrom a LVP waveform to stored threshold values.

In step 420, a notification regarding the determined optimization of theblood pump performance is generated and displayed. The notification canbe accessed in from a memory in the controller and according to thedetermined optimization and generated for display. The notificationregarding the optimization of blood pump performance can be displayed inthe user interface of FIG. 3. In some implementations, the notificationregarding the optimization of the blood pump performance is displayed onthe main screen. In some implementations, the notification regarding theoptimization of the blood pump performance is displayed as a pop-up orwarning. The notification may suggest that blood pump motor speed beincreased or decreased, or may indicate that there is a positioningproblem or risk of a suction event. In some implementations, thenotification may further indicate a recommendation for addressing apositioning issue or suction event, for example by recommending that theblood pump motor speed by increased or decreased, or that the blood pumpbe moved in a particular direction by a certain distance. In someimplementations, the recommended change in motor speed may exceed aspeed of a currently used blood pump, and the notification may recommendchanging the blood pump type.

In some implementations, the displayed notification is interactive andthe controller can take action with regard to recommended changes inmotor speed based on an input from a clinician. In otherimplementations, the notification may indicate that the recommendedchange in motor speed has already been automatically made by thecontroller.

FIG. 5A shows a user interface 500 for a heart pump controllerillustrating an intermittent or diastolic suction event at the bloodpump. The user interface 500 includes components similar to the userinterface 300, and not all components are labelled or displayed here forsimplicity. The user interface 500 includes a first plot 505 showing anaortic pressure waveform 504 and a LVP waveform 506, and a second plot507 showing a motor current waveform. The user interface also includesan indication of aortic pressure 508 over the aortic pressure waveform504 including a minimum and maximum value, an indication of LVP 512 overthe LVP waveform 506 including a minimum and maximum value. Anindication of current motor speed 510, a warning pop-up 514, andinstructions or recommendations for addressing the warning pop-up 516are also included in the user interface 500.

The aortic pressure waveform 504 and LVP waveform 506 measured by thecontroller based on pressure readings and motor current of the bloodpump are helpful in detecting diastolic and intermittent suction eventsat the blood pump caused by insufficient blood volume in the heart.During such suction events, the LVP waveform 506 falls below zero in thefirst plot 505 in early diastole but recovers by the end diastolicpressure point. The systolic phase of the LVP waveform 506 is normal.These events may also be detected by the indication of LVP 512 andindication of aortic pressure 508, as the maximum indication of LVP 512is typically normal and greater than the maximum indication of aorticpressure 508, while the minimum indication of LVP 512 is abnormal and isvery low or less than zero during intermittent and diastolic suctionevents. Accordingly, the minimum value of the indication of LVP 512provides an early indicator of diastolic suction. The controller canissue a warning 514 based on a comparison of the minimum value of theindication of LVP 512 to a threshold value, for example, 0 mmHg, −10mmHg, −20 mmHg, −30 mmHg, −40 mmHg, or any other suitable thresholdvalue. In some implementations, the comparison of the minimum value ofthe indication of LVP 512 may be used to determine a level of risk orseverity of the suction event, for example with 0 mmHg signifying aborderline or low risk, −10 mmHg signifying a mild suction risk, −20mmHg signifying a moderate risk of suction, etc. The controller canfurther provide recommendations 516 to a physician, nurse, or technicianfor how to react to the warning 514 to address and correct the suctionevent. For example, the controller may provide a recommendation to checkadditional cardiac metrics to determine a cause of the suction event orcheck on patient health before adjusting the positioning or cardiacsupport level of the blood pump. The controller may also provideinstructions or recommendations to check the positioning of the bloodpump based on the suction event detection and further may recommend achange in the level of support provided by the blood pump by a change tothe motor current 510.

FIG. 5B shows a user interface 501 for a heart pump controllerillustrating a continuous suction even at the blood pump. Like the userinterface 500 in FIG. 5A, the user interface 501 includes componentssimilar to the user interface 300, and not all components are labelledor displayed here for simplicity. The user interface 501 includes afirst plot 525 showing an aortic pressure waveform 524 and a LVPwaveform 526, and a second plot 527 showing a motor current waveform.The user interface also includes an indication of aortic pressure 528over the aortic pressure waveform 524 including a minimum and maximumvalue, an indication of LVP 532 over the LVP waveform 526 including aminimum and maximum value. An indication of current motor speed 530, awarning pop-up 534, and instructions or recommendations for addressingthe warning pop-up 536 are also included in the user interface 501.

Similar to the process by which intermittent (diastolic) suction eventsare determined and shown by the displayed LVP and aortic pressure inFIG. 5A, the determination of continuous or systolic suction events isinformed by the LVP waveform 526 and aortic pressure waveform 524,indication of LVP 528, and indication of aortic pressure 532. Bydisplaying these and other cardiac metrics to a user via the userinterface 501, a user such as a clinician or physician can be aware ofcontinuous suction events and can appropriately react to address them.Continuous suction events are typically caused by poor positioning ofthe blood pump or a cardiac structure blocking the blood pump inflow(e.g., pump inlet 114). During a continuous suction event, the LVPwaveform 526 falls below zero during diastole and never rises above theaortic pressure waveform 524 during systole. Additionally, during acontinuous suction event the maximum value of the indication of LVP 532is abnormal and is typically much lower than a maximum value of theindication of aortic pressure 528, while the minimum value of theindication of LVP 532 is abnormal and is less than zero. The LVEDPcalculated from the LVP waveform 526, if displayed, is equal to zero.

As in the case of the intermittent (diastolic) suction event of FIG. 5A,a warning 534 and recommendations 536 may be displayed when a continuoussuction event is detected. The recommendations 536 displayed when acontinuous suction event is detected may be the same or different fromthe recommendations 516 displayed during an intermittent suction event.

FIG. 5C shows a user interface 502 for a heart pump controllerillustrating a metric trend screen. The trend screen includes a firstplot 540 displaying a cardiac output trend waveform 542, a blood pumpflow trend waveform 544, and a native cardiac output trend waveform 546,as well as associated values of cardiac output, blood pump flow, andnative cardiac output for rapid assessment by a physician. The userinterface 502 metric trend screen also includes a second plot 548displaying a mean aortic pressure trend waveform 550, and an LVEDP trendwaveform 552, as well as associated values of mean aortic pressure 554and LVEDP 556. The user interface 502 also includes an indication ofmotor speed of a blood pump 560, blood pump flow 562, cardiac output564, and cardiac power output 558.

The metric trend screen of the user interface 502 is accessible to aphysician to further illustrate the historic data associated withvarious cardiac parameters over time. Such historic data can helpphysicians to understand the progress of the patient's cardiac health aswell as to identify events taking place. For example, the metric trendscreen of the user interface 502 shown in FIG. 5C displays cardiacoutput trend waveform 542, blood pump flow trend waveform 544, nativecardiac output trend waveform 546, aortic pressure trend waveform 550,and a LVEDP trend waveform 552 all of which are relatively stable overtime. However, changes or trends in these waveforms over time canindicate suction events or risk of suction. The LVEDP trend waveform 552should be stable over the course of providing cardiac support to thepatient. A low and/or declining LVEDP trend waveform 552 indicates thatthere is an increasing risk of diastolic suction. Having this waveformreadily available to a physician enables the physician to monitor therisk of suction events. In order to determine a cause of the suction, aphysician can consult the metric trend screen of the user interface 502,where an LVEDP trend waveform 552 that is high but abruptly drops tozero implies a continuous or systolic suction event, while a low LVEDPtrend waveform 552 that hovers around 0 implies an intermittent ordiastolic suction event. The display of these trends and values is madepossible by the calculation of the metrics by the controller algorithmfrom the blood pump motor current and aortic pressure, and physiciansare able to make informed decisions about patient care based on thevalues and trends.

Beyond merely providing indications of suction events, the display ofvarious waveforms and average cardiac metric values can also provideinformation to physicians that enable them to determine a positioningerror of the blood pump. For example, by observing changes in the LVPwaveform (e.g., 506 in FIG. 5A or 526 in FIG. 5B) with respect to theaortic pressure waveform (e.g., 504 in FIG. 5A or 524 in FIG. 5B) aphysician or technician can determine that a blood pump has migratedinto the left ventricle and is no longer providing appropriate supportas a result. When a blood pump migrates into the left ventricle, achange in the shape of the LVP waveform provides instant feedback thatthe positioning error has occurred. A comparison of the LVP maximum andminimum values to the aortic pressure maximum and minimum values canindicate to the physician that the aortic pressure values have begun toreflect a left-ventricular signal instead of the aortic pressure.Meanwhile the LVEDP remains stable, confirming that there are noventricular structures impairing the flow area despite the migration ofthe pump.

The display of the waveforms can also be useful during a repositioningof a pump that has migrated into the left ventricle. The separate LVPand aortic pressure waveforms can be viewed to confirm a distinct aorticpressure signal and can provide instantaneous feedback to the physicianor technician during repositioning. Comparison of the LVP indication andthe aortic pressure indication can also be viewed and can confirm thatrepositioning of the blood pump as the aortic pressure values separatefrom the LVP values.

In addition to displaying the waveforms and cardiac metric values, theuser interface may provide a warning and/or recommendations if a bloodpump positioning problem is detected. The recommendations may includesuggestions to decrease a pump flow rate or motor speed and to access arepositioning guide.

In addition to displaying cardiac waveforms and values that can indicateto physicians about suction events and positioning problems, thecalculated cardiac parameters and metrics can also inform weaningdecisions. FIG. 5D shows a user interface 504 for a heart pumpcontroller illustrating changes in heart function during weaning ascaptured by the displayed metrics. The user interface includes a firstplot 575 showing an aortic pressure waveform 574 and a LVP waveform 576,and a second plot 577 showing a motor current waveform. The userinterface also includes an indication of aortic pressure 578 over theaortic pressure waveform 574 including a minimum, maximum, and meanvalue, and an indication of LVP 582 over the LVP waveform 576 includinga minimum, maximum, and end-diastolic (LVEDP) value. An indication ofcurrent motor speed 580, an indication of blood pump flow rate 588, anindication of cardiac output 586, and an indication of cardiac poweroutput 584 are also included in the user interface 504.

The LVP waveform 576 and aortic pressure waveform 575 displayed in FIG.5D are illustrative of a recovered patient with stable hemodynamics. TheLVEDP should be stable during weaning process, as the native heart takesover function and clears excess left-ventricular volume. The cardiacoutput should similarly be stable during weaning as the native hearttakes over for the pump output, and the cardiac power output should bestable and preferably within the range required by decision protocols ofthe specific institution. The progress of a recovered patient duringweaning can also be visualized on the metric trend screen, where anincrease in the native cardiac output (e.g., 546 in FIG. 5C) occurs withdecreasing blood pump flow (e.g., 544 in FIG. 5C) as the support fromthe blood pump is decreased over time. The native heart takes over thefunction from the blood pump during the weaning process, and the cardiacoutput (e.g., 542 in FIG. 5C) remains stable. The LVEDP (e.g., 552 inFIG. 5C) is stable or declining as the native heart takes over. Finally,the cardiac power output (e.g., 558 in FIG. 5C) is stable.

In the case of a patient with a worsening condition, the LVEDP is likelyto rise during a weaning attempt, as the heart is unable to pump theexcess blood volume and the left-ventricular volume increases. The LVPwaveform 576 and aortic pressure waveform 574 may decrease during thistime. The cardiac output 586 and cardiac power output 584 also decreaseduring weaning of a sick patient as the native heart fails to compensatefor the decreased support from the blood pump. The declining function ofa sick patient during weaning can also be visualized on the metrictrends screen, where the native cardiac output (e.g., 546 in FIG. 5C)may decline over time as the patient becomes more dependent on the bloodpump support. The LVEDP waveform (e.g., 552 in FIG. 5C) may rise as theheart is unable to pump the blood and the LVP increases. The cardiacpower output (e.g., 558 in FIG. 5C) decreases with lower total poweroutput.

FIG. 6 shows a process 600 for determining a cardiac power output anddisplaying a recommendation of modulation of pump support to a user. Theprocess 600 can be performed using the intravascular heart pump system100 of FIG. 1, or any other suitable heart pump. The cardiac poweroutput, and historical trends in the cardiac power output over time, canbe interpreted and evaluated by a physician in an intensive care settingor catheterization lab to monitor metric trends during the weaningprocess and to assess patient readiness to wean the heart from the bloodpump support. Additionally, cardiac output, native cardiac output, andLVEDP can also be generated and displayed to the physician to informdecisions about weaning of a patient.

In order to determine the cardiac power output of a patient, thealgorithm proceeds according to the following process. In step 602, themotor of a heart pump is operated. The motor may be operated at aconstant rotational speed. In step 604, the aortic pressure is measured.The aortic pressure may be measured by a pressure sensor coupled to theheart pump, by a separate catheter, by a noninvasive pressure sensor, orby any other suitable sensor. The pressure sensor may be a fluid-filledtube, a differential pressure sensor, hydraulic sensor, piezo-resistivestrain gauge, optical interferometry sensor or other optical sensor,MEMS piezo-electric sensor, or any other suitable sensor. In someimplementations, ventricular pressure is measured in addition to or inalternative to measuring aortic pressure.

In step 606, the current delivered to the motor is measured and themotor speed is measured. The current may be measured using a currentsensor or by any other suitable means.

In step 608, the pulse pressure wave is calculated from the aorticpressure waveform by subtracting the minimum aortic pressure from themaximum aortic pressure. The mean aortic pressure may also be extractedfrom the average of the aortic pressure waveform. In step 610 the nativecardiac output is derived from the pulse pressure. To calculate thenative cardiac output, a relationship between the pulse pressure and thenative cardiac output by a linear scaling factor must first bedetermined. The scaling factor is specific to both the patient and thecondition, and may be derived from internal or external calibrationmethods. In step 612, the pump flow is derived from the measured motorcurrent and motor speed. In step 614, the total cardiac output isdetermined by adding the pump flow to the native cardiac output. In step616, the cardiac power output is calculated from the total cardiacoutput and the mean aortic pressure.

In step 618, a recommendation for modulation of the pump support to theheart is determined based on the calculated cardiac power output. Forexample, a recommendation to decrease pump support to wean the patientfrom cardiac support may be determined if the calculated cardiac poweroutput, or comparison of the calculated cardiac power output to athreshold or historical value, indicates that the patient has improvedcardiac function. In another example, a recommendation to increase pumpsupport to the patient may be determined if the calculated cardiac poweroutput, or comparison of the calculated cardiac power output to athreshold or historical value, indicates that the cardiac function hasworsened. Finally, in step 620, the recommendation for modulation ofpump support is generated for display and displayed on a user interface.In some implementations, the cardiac power output, and additionallyother calculated metrics and parameters, are also generated for displayand displayed with the recommendation for modulation of pump support.The calculated cardiac power output, and optionally the historical viewof the cardiac power output over time, allows the clinician to view andmake decisions based on the trends of the cardiac power output, forexample to make decisions related to the weaning of a patient from bloodpump support. Displaying these metric trends can help a clinician toevaluate the displayed recommendation of modulate and to support weaningdecisions or other decisions to change the level of support provided bythe blood pump.

The cardiac power output is a product of the cardiac output and the meanaortic pressure, and is indicative of the true measure of power comingfrom the heart and the pump immediately distal to the aortic valve. Thisis measureable based on the positioning of the pressure sensor at thepump outflow of the blood pump and the understanding of the operation ofthe blood pump with respect to the cardiac parameters. Clinicians canuse the native cardiac power output as a measure of the overall healthof the heart, as it represents the power being output by the heartitself. The trends of the native cardiac power output can be used by aclinician to determine if the native heart output is improving ordeclining and can make clinical decisions about the support beingprovided by the blood pump and pharmaceutical therapies based on thesetrends. The determination of cardiac power output by the algorithmdescribed above is more reliable and accurate than such conventionalmethods of determination.

FIG. 7 shows a process 700 for recommending an adjustment to a motorspeed based on measured and calculated cardiac parameters. The process700 can be performed using the intravascular heart pump system 100 ofFIG. 1, or any other suitable heart pump. The process 700 includes steps702-716 which are substantially similar to steps 402-416 in FIG. 4.These steps are recited briefly here, but a person of ordinary skillwill understand that the alternatives and additional details included inthe description of the corresponding steps in FIG. 4 also apply to steps702-716 of FIG. 7.

As in process 400 in FIG. 4, in step 702, the motor of a heart pump isoperated. The motor may be operated at a constant rotational speed. Instep 704, the aortic pressure is measured. As in process 400 in FIG. 4,the aortic pressure may be measured by a pressure sensor coupled to theheart pump or by a separate catheter. The sensor may be a fluid-filledtube, a differential pressure sensor, hydraulic sensor, piezo-resistivestrain gauge, optical interferometry sensor or other optical sensor,MEMS piezo-electric sensor, or any other suitable sensor. In step 706,the current delivered to the motor is measured and the motor speed ismeasured. In step 708, the pressure differential across a cannula of theblood pump is determined based on the measured motor current and motorspeed, by using a lookup table or accessing a function which accountsfor the measured motor current for a known motor speed, and optionallyother parameters as discussed in regard to process 400 in FIG. 4.

In step 710, a cardiac parameter is calculated based on the pressuredifferential across the cannula of the blood pump and the aorticpressure. The cardiac parameter may be one of a LVEDP, LVP, aortic pulsepressure, mean aortic pressure, pump flow, pressure gradient, or heartrate. These cardiac parameters can each be used by clinicians as ameasure of various aspects of cardiac health and function. The trends ofeach of the cardiac parameters over time can be used by a clinician todetermine if the native heart output is improving or declining and canmake clinical decisions about the support being provided by the bloodpump and pharmaceutical therapies based on these trends. In someimplementations, more than one cardiac parameter is calculated based onthe pressure differential across the cannula of the blood pump and theaortic pressure.

In step 712, the calculated cardiac parameter is recorded in the memory.By accessing the recorded cardiac parameters stored in the memory, ahistorical view of the cardiac parameter over time can be accessed by auser or displayed on a display console as a trend line.

In step 714, a heart function parameter is determined based on thecalculated cardiac parameter. The heart function parameter can be any ofcardiac output, cardiac power output, native cardiac output, nativecardiac power output, cardiac contractility, cardiac relaxation, fluidresponsiveness, volume status, cardiac unloading index, cardiac recoveryindex, left-ventricular diastolic function, left-ventricular diastolicelastance, left-ventricular systolic elastance, stroke volume, heartrate variability, stroke volume variability, pulse pressure variability,aortic compliance, vascular compliance, or vascular resistance. Theseheart function parameters can be calculated from the calculated cardiacparameter and other available measured parameters. The heart functionparameters offer additional information to clinicians about the heartfunction. In some implementations, the heart function parameter is alsorecorded in the memory in order to provide historical data and heartfunction parameter trends with respect to time. In some implementations,more than one heart function parameter is determined.

In step 716, the calculated cardiac parameter and/or the heart functionparameter is generated for display and is displayed to a user. Thecalculated cardiac parameter and/or heart function parameter is accessedfrom the memory and is generated for display as a number value, maximumand minimum value over a period of time, and/or as a historical trendover time. The cardiac parameter and heart function parameter is thendisplayed to a clinician on a display, such as display 300 in FIG. 3.The calculated cardiac parameter, the heart function parameter, andoptionally the historical views of the cardiac parameter and/or heartfunction parameter over time, allows a clinician to view and makedecisions based on the trends of the cardiac parameter and heartfunction parameter.

The display and/or the determination of the cardiac parameter and heartfunction parameter can be continuous or nearly continuous while theheart pump is implanted in the heart. This can be advantageous overconventional catheter-based methods that only allow sampling of cardiacfunction at specific times during the cardiac cycle or at discretepoints in time. For example, continuous monitoring of the cardiacparameter may allow more rapid detection of cardiac deterioration.Continuous monitoring of the cardiac parameter and heart functionparameter can illustrate changes in the heart condition over time.Additionally, if the cardiac assist device is already in the patient,the cardiac function can be measured without having to introduce anadditional catheter into a patient. The cardiac parameter and/or heartfunction parameter may be displayed as shown in the user interface ofFIG. 3 or using any other suitable user interface or report.

In step 718, a recommended change to the motor speed is determined basedon the calculated cardiac parameter and heart function parameter. Therecommended change to the motor speed may be determined based on acomparison of the cardiac parameter and/or the heart function parameterto a threshold value. Subsequently, the cardiac parameter and/or theheart function parameter, or a difference between the cardiac parameteror heart function parameter and the threshold value may be used todetermine a required increase or decrease in pump flow, and the increaseor decrease in pump flow may be used to determine a corresponding motorspeed using a look-up table or other function.

In step 720, the recommended change to the motor speed is generated fordisplay and is displayed. The recommended change to the motor speed canbe displayed in the user interface of FIG. 3. In some implementations,the recommended change to the motor speed is displayed on the mainscreen. In some implementations, the recommended change to the motorspeed is displayed as a pop-up or warning. In step 722, a user input isaccepted in response to the displayed recommended change to the motorspeed. In step 724, the motor speed is adjusted according to the userinput. The motor speed is adjusted by changing the power delivered tothe motor. The motor speed may be adjusted to be faster or slower than acurrent speed of the motor depending on the user input in response tothe recommended change in motor speed. The power delivered to the motorcan be adjusted automatically by a controller or manually (e.g., by ahealthcare professional). The degree of support can be increased when apatient's heart function is deteriorating or the degree of support canbe decreased when a patient's heart function is recovering, thusallowing the patient to be gradually weaned off of the therapy. This canallow the device to dynamically respond to changes in heart function topromote heart recovery. It can also be used to intermittently modulatepump support and to diagnose how the heart reacts, e.g., if it can takeover the pumping function from the heart pumping device.

FIG. 8 shows a process 800 for recommending an adjustment to a motorspeed based on a cardiac power output and LVEDP. The process 800 can beperformed using the intravascular heart pump system 100 of FIG. 1, orany other suitable heart pump. The process 800 follows the steps ofprocess 700 shown in FIG. 7 for the particular case of determining arecommendation of an adjustment to the motor speed based on the cardiacpower output and LVEDP. In step 802, the motor of a heart pump isoperated. The motor may be operated at a constant rotational speed. Instep 804, the aortic pressure is measured. The aortic pressure may bemeasured by a pressure sensor coupled to the heart pump, by a separatecatheter, by a noninvasive pressure sensor, or by any other suitablesensor. The pressure sensor may be a fluid-filled tube, a differentialpressure sensor, hydraulic sensor, piezo-resistive strain gauge, opticalinterferometry sensor or other optical sensor, MEMS piezo-electricsensor, or any other suitable sensor. In some implementations,ventricular pressure is measured in addition to or in alternative tomeasuring aortic pressure. In step 806, the current delivered to themotor is measured and the motor speed is measured. The current may bemeasured using a current sensor or by any other suitable means.

In step 808, the pressure differential across a cannula of the bloodpump is determined based on the measured motor current and motor speed.The controller may access a look-up table, such as a look-up table basedon the relationship between the differential pressure and the motorcurrent for a known motor speed in FIG. 2A. The controller mayalternatively utilize a function describing the relationship between thedifferential pressure and the motor current to determine thedifferential pressure across the cannula of the blood pump associatedwith the measured motor current and a known motor speed. The controllermay also take into account various other parameters in the determinationof the differential pressure, for example characteristics of the bloodpump, pump controller or console, environmental parameters, and motorspeed settings, in order to more accurately determine the pressuregradient across the cannula.

In step 810, a LVEDP and a cardiac power output are determined based onthe aortic pressure and the pressure gradient across the blood pumpcannula. The LVEDP is calculated by subtracting the pressure gradientacross the cannula determined from the motor current from the aorticpressure and selecting the end-diastolic point from the cardiac cycle.The cardiac power output is calculated by first determining a nativecardiac output from a pulse pressure, determining a total cardiac outputbased on the pump flow, and finally using the cardiac output with themean arterial pressure to calculate the cardiac power output. In someimplementations, if the blood pump is a right heart blood pump the rightventricular pressure is determined.

In step 812, a recommended adjustment to the motor speed of the bloodpump is determined. The recommended adjustment to the motor speed may bedetermined based on a comparison of the LVEDP, the cardiac power output,the cardiac output, and/or the mean aortic pressure to a thresholdvalue. Subsequently, the above compared cardiac parameter, or adifference between the compared cardiac parameter or heart functionparameter and the threshold value may be used to determine a requiredincrease or decrease in pump flow, and the increase or decrease in pumpflow may be used to determine a corresponding motor speed using alook-up table or other function.

In step 814, the recommended adjustment to the motor speed of the bloodpump is generated for display and is displayed. The recommended changeto the motor speed can be displayed in the user interface of FIG. 3. Insome implementations, the recommended change to the motor speed isdisplayed on the main screen. In some implementations, the recommendedchange to the motor speed is displayed as a pop-up notification orwarning.

FIG. 9 shows a process 900 for recommending a higher flow device fortreatment based on measured and calculated cardiac parameters. Theprocess 900 includes steps 902-918 which are substantially similar tosteps 702-718 in FIG. 7. These steps are recited briefly here, but aperson of ordinary skill will understand that the alternatives andadditional details included in the description of the correspondingsteps in FIG. 7 also apply to steps 902-918 of FIG. 9.

In step 902, the motor of a heart pump is operated. In step 904, theaortic pressure is measured. In step 906, the current delivered to themotor is measured and the motor speed is measured. In step 908, thepressure differential across a cannula of the blood pump is determinedbased on the measured motor current and the measured motor speed. Instep 910, a cardiac parameter is calculated based on the pressuredifferential across the cannula of the blood pump and the aorticpressure. In step 912, the calculated cardiac parameter is recorded inthe memory. The calculated cardiac parameter may be any of LVEDP, LVP,aortic pulse pressure, mean aortic pressure, pump flow, pressuregradient, or heart rate. In step 914, a heart function parameter isdetermined based on the calculated cardiac parameter. The heart functionparameter may be any of cardiac output, cardiac power output, nativecardiac output, native cardiac power output, cardiac contractility,cardiac relaxation, fluid responsiveness, volume status, cardiacunloading index, cardiac recovery index, left-ventricular diastolicfunction, left-ventricular diastolic elastance, left-ventricularsystolic elastance, stroke volume, heart rate variability, stroke volumevariability, pulse pressure variability, aortic compliance, vascularcompliance, or vascular resistance. In step 916, the calculated cardiacparameter and/or the heart function parameter is generated for displayand is displayed to a user. The recorded cardiac parameter is accessedin the memory and is processed for display as an instantaneous value, aset of maximum and minimum values over a period of time, and/or as ahistorical trend over time. The recorded cardiac parameter is thendisplayed to a user. In some implementations, the calculated heartfunction parameter is also stored and displayed as a trend over time. Instep 918, a recommended change to the motor speed is determined based onthe calculated cardiac parameter and heart function parameter.

In step 920, the recommended change to the motor speed is compared to athreshold value. The threshold value may be a value associated with theblood pump, indicating a maximum or minimum operational motor speed. Therecommended change to the motor speed is compared to a threshold valuein order to determine if the current blood pump is capable of operatingat the required speed and/or whether the current blood pump is theoptimal blood pump for operation at the required speed.

In step 922, an appropriate blood pump for operation at the recommendedmotor speed is determined based on the comparison to the thresholdvalue. The appropriate blood pump may be determined by consulting alook-up table including properties and characteristics of variousavailable blood pumps. The determination of the appropriate blood pumpfor operation at the recommended motor speed may also take into accountthe calculated cardiac parameter and/or the heart function parameter.Accounting for the calculated cardiac parameter and/or the heartfunction parameter may enable the controller to make a recommendationbased not only on the recommended pump speed, but also on the generalheart function and health. In some cases, it may be unwise to change toa different blood pump because of the poor cardiac function of apatient. Taking the calculated cardiac parameter and heart function intoaccount, or alternatively, displaying a warning to the clinician withthe recommendation, prevents changing the blood pump to adjust a motorspeed when it would be unwise to do so.

In step 924, the determined appropriate blood pump is generated fordisplay and is displayed. The cardiac parameter and heart functionparameter can be displayed to a clinician on a display, such as display300 in FIG. 3. In some implementations, the recommended motor speed isalso displayed. As noted above, additional information or warnings tothe clinician can also be displayed when a different blood pump isrecommended, prompting the clinician to follow protocols or to makeadditional determinations of heart function and health before acting onthe recommendation.

FIG. 10 shows a process 1000 for recommending a pharmaceutical therapybased on measured and calculated cardiac parameters. For example, thetitration of medicaments, including inotropes and vasopressors, can bemonitored and determined based on the evaluation of cardiac metrics suchas cardiac output, mean aortic pressure and others. Further, volumestatus and fluid responsiveness can be monitored by evaluation of theLVEDP over time. The process 1000 for recommending a pharmaceuticaltherapy includes steps 1002-1020 which are substantially similar tosteps 702-720 in FIG. 7. These steps are recited briefly here, but aperson of ordinary skill will understand that the alternatives andadditional details included in the description of the correspondingsteps in FIG. 7 also apply to steps 1002-1020 of FIG. 10.

In step 1002, the motor of a heart pump is operated. In step 1004, theaortic pressure is measured. In step 1006, the current delivered to themotor is measured and the motor speed is measured. In step 1008, thepressure differential across a cannula of the blood pump is determinedbased on the measured motor current and measured motor speed. In step1010, a cardiac parameter is calculated based on the pressuredifferential across the cannula of the blood pump and the aorticpressure. The calculated cardiac parameter may be any of LVEDP, LVP,aortic pulse pressure, mean aortic pressure, pump flow, pressuregradient, or heart rate. In step 1012, the calculated cardiac parameteris recorded in the memory. In step 1014, a heart function parameter isdetermined based on the calculated cardiac parameter. The heart functionparameter may be any of cardiac output, cardiac power output, nativecardiac output, native cardiac power output, cardiac contractility,cardiac relaxation, fluid responsiveness, volume status, cardiacunloading index, cardiac recovery index, left-ventricular diastolicfunction, left-ventricular diastolic elastance, left-ventricularsystolic elastance, stroke volume, heart rate variability, stroke volumevariability, pulse pressure variability, aortic compliance, vascularcompliance, or vascular resistance. In some implementations, the heartfunction parameter is also stored in the memory. In step 1016, thecalculated cardiac parameter and/or the heart function parameter isdisplayed.

In step 1018, a recommended therapy is determined based on thecalculated cardiac parameter and heart function parameter. Therecommended therapy is based on the calculated cardiac parameter andheart function parameter. In some implementations, the recommendedtherapy is based on a comparison of the calculated cardiac parameterand/or the heart function parameter to a threshold value. In someimplementations, the recommended therapy is based on a comparison of achange in the calculated cardiac parameter and/or the heart functionparameter over a period of time. In some implementations, therecommended therapy is determined by accessing a look-up table andextracting a dosage corresponding to a current value of the calculatedcardiac parameter and heart function parameter.

For example, a combination of the calculated cardiac parameters ofnative cardiac output, LVEDP, and cardiac power output can be analyzedby the algorithm and compared to threshold values to determine that apharmaceutical intervention is warranted or would be beneficial. Thealgorithm may determine that the administration of inotropes iswarranted, and further analysis such as consultation of a look-up tableof dosages may allow the algorithm to provide the recommendation thatthe clinician administer inotropes as well as a recommendation for theparticular dosage or titration with which the therapy should beadministered.

Monitoring and analyzing additional cardiac parameters allows thealgorithm to also provide information and recommendations to cliniciansto modulate the fluid intake of a patient or the administration ofdiuretics to the patient. By measuring and determining cardiacparameters such as native output, LVEDP, and variation within aorticpulse pressure, the algorithm can identify the status of patients andwhether they are in an optimum fluid window) and can also assess andreport on the fluid responsiveness of a patient.

In step 1020, a recommended dosage associated with the recommendedtherapy is determined. The recommended dosage is based on the calculatedcardiac parameter and heart function parameter. In some implementations,the recommended dosage is based on a comparison of the calculatedcardiac parameter and/or the heart function parameter to a thresholdvalue. In some implementations, the recommended dosage is based on acomparison of a change in the calculated cardiac parameter and/or theheart function parameter over a period of time. In some implementations,the recommended dosage is determined by accessing a look-up table forthe recommended therapy and extracting a dosage corresponding to acurrent value of the calculated cardiac parameter and heart functionparameter.

In step 1022, the recommended therapy and the recommended dosage aregenerated for display and are displayed. The recommended therapy and therecommended dosage can be displayed in the user interface of FIG. 3. Insome implementations, the recommended therapy and the recommended dosageis displayed on the main screen. In some implementations, therecommended therapy and the recommended dosage is displayed as a pop-upor warning. In a similar fashion as in the process 900, the recommendedtherapy and recommended dosage may be displayed with a warning to aclinician to prompt the clinician to follow specific protocols or tomonitor or check other cardiac function parameters before administeringany therapy.

FIG. 11 shows a process 1100 for alerting a user of predicted adversecardiac events based on measured and calculated cardiac parameters. Theprocess 1100 includes steps 1102-1120 which are substantially similar tosteps 702-720 in FIG. 7. These steps are recited briefly here, but aperson of ordinary skill will understand that the alternatives andadditional details included in the description of the correspondingsteps in FIG. 7 also apply to steps 1102-1120 of FIG. 11.

In step 1102, the motor of a heart pump is operated. In step 1104, theaortic pressure is measured. In step 1106, the current delivered to themotor is measured and the motor speed is measured. In step 1108, thepressure differential across a cannula of the blood pump is determinedbased on the measured motor current and measured motor speed. In step1110, a cardiac parameter is calculated based on the pressuredifferential across the cannula of the blood pump and the aorticpressure. The calculated cardiac parameter may be any of LVEDP, LVP,aortic pulse pressure, mean aortic pressure, pump flow, pressuregradient, or heart rate. In step 1112, the calculated cardiac parameteris recorded in the memory. In step 1114, a heart function parameter isdetermined based on the calculated cardiac parameter. The heart functionparameter may be any of cardiac output, cardiac power output, nativecardiac output, native cardiac power output, cardiac contractility,cardiac relaxation, fluid responsiveness, volume status, cardiacunloading index, cardiac recovery index, left-ventricular diastolicfunction, left-ventricular diastolic elastance, left-ventricularsystolic elastance, stroke volume, heart rate variability, stroke volumevariability, pulse pressure variability, aortic compliance, vascularcompliance, or vascular resistance. In some implementations, the heartfunction parameter is also stored in the memory. In step 1116, thecalculated cardiac parameter and/or the heart function parameter isgenerated for display and is displayed to a user. The calculated cardiacparameter and/or the heart function parameter can be generated fordisplay as an instantaneous value, a maximum and minimum value over aperiod of time, and/or as a historical trend over time. The calculatedcardiac parameter and/or the heart function parameter is then displayedto the user.

In step 1118, the calculated cardiac parameter and/or the heart functionparameter are compared to a threshold value. In some implementations,the set threshold value is a system value set within the controller. Insome implementations, the set threshold value is set by a clinicianbased on a patient's history and health. In some implementations, theset threshold value is a previous value of the cardiac metric, forexample, a previous value measured or calculated a predetermined amountof time before. In step 1120, it is determined whether the calculatedcardiac parameter and/or the heart function parameter satisfy thethreshold value. The set threshold value is set such that a cardiacparameter or heart function parameter which satisfies the threshold isan indication or possible indication of an early warning signal of acardiac or ischemic event in progress.

Many adverse events can be predicted based on the determination ofcardiac parameters and comparison of the cardiac parameters or theirtrends over time to a threshold value. Additionally, the display ofthese additional cardiac parameters to healthcare professionals in realtime and including historical data enables physicians to betterunderstand patient health and to predict and address possible adverseevents. For example, additional ischemic events, conductionabnormalities, or bleeding and hemolysis can be detected and addressedbased on the cardiac parameters calculated and displayed according tothe algorithm described herein. Based on the prediction of such adverseevents, a physician can make clinical decisions such as optimization ofsupport to maximize native recovery, and balancing of left andright-sided support.

In step 1122, an alarm is triggered with regard to the cardiac parameterand/or the heart function parameter. The alarm can be an audible alarmor can be displayed in the user interface of FIG. 3. In someimplementations, the alarm can be sent, via a Wi-Fi network, blue toothsignal, or cellular signal, to a clinician by page, text, or email. Insome implementations, the warning is displayed on the main screen. Insome implementations, the warning is displayed as a pop-up message. Insome implementations, the warning can be turned off or muted by aclinician.

FIG. 12 shows a process 1200 for balancing right and left-sided bloodpump devices during bi-ventricular support based on measured andcalculated cardiac parameters. When both left-sided and right-sideddevices provide simultaneous cardiac support, it can be challenging tobalance the right-sided and left-sided output to maintain appropriatepressures in the lungs and limit the risk of pulmonary edema. Measuringnative cardiac outputs and total outputs along with the pulmonary arterypressure and left-ventricular diastolic pressure enable clinicians tobetter balance the right and left side support.

In step 1202, the first motor of a first blood pump is operated. Thismay be, for example a right-sided device placed in the right ventricleand pulmonary artery of the heart. In step 1204, the second motor of thesecond blood pump is operated. This may be, for example, a left-sideddevice placed in the left ventricle and aorta of the heart. The firstmotor and the second motor are simultaneously operated to providesupport to both sides of the heart. At step 1206, the pressure at thepump outlet is measured. For the second pump, a left-side device, thisis the aortic pressure. For the first pump, a right-sided device, thisis the pulmonic pressure. The aortic pressure may be measured by apressure sensor coupled to the heart pump, by a separate catheter, by anoninvasive pressure sensor, or by any other suitable sensor. Thepressure sensor may be a fluid-filled tube, a differential pressuresensor, hydraulic sensor, piezo-resistive strain gauge, opticalinterferometry sensor or other optical sensor, MEMS piezo-electricsensor, or any other suitable sensor. In some implementations,ventricular pressure is measured in addition to or in alternative tomeasuring aortic pressure.

At step 1208, the first motor current and first motor speed of the firstblood pump are measured and the second motor current and second motorspeed of the second blood pump are measured. In step 1210, the firstpressure differential across a first cannula of the first blood pump isdetermined based on the measured first motor current and measured firstmotor speed, and the second pressure differential across a secondcannula of the second blood pump is determined based on the measuredsecond motor current and measured second motor speed. The first pressuredifferential and the second pressure differential may be determined byusing a lookup table or accessing a function which accounts for themeasured motor current, measured motor speed, and optionally otherparameters.

In step 1212, a first cardiac parameter is calculated based on the firstpressure differential across the first cannula of the first blood pumpand the first pump outlet pressure, and a second cardiac parameter iscalculated based on the second pressure differential across the secondcannula of the second blood pump and the second pump outlet pressure.The first cardiac parameter, from the right-sided device may be any of aright ventricular pressure, a right ventricular end-diastolic pressure,a pulmonary artery pressure, a right arterial pressure, a central venouspressure, or a blood pump flow rate. The second cardiac parameter, fromthe left-sided device, may be any of a LVEDP, LVP, aortic pulsepressure, mean aortic pressure, pump flow, pressure gradient, heartrate, or right arterial pressure. These cardiac parameters can each beused by clinicians as a measure of various aspects of cardiac health andfunction and to better balance the right and left-sided devices toprovide balanced cardiac support.

Further, the trends of each of the cardiac parameters over time can beused by a clinician to determine if the native heart output is improvingor declining and can make clinical decisions about the support beingprovided by the blood pumps and pharmaceutical therapies based on thesetrends. In some implementations, more than one cardiac parameter iscalculated based on the pressure differential across the cannula of theblood pump and the aortic pressure.

In step 1214, a heart function parameter is determined based on thecalculated first cardiac parameter and/or the calculated second cardiacparameter. The heart function parameter can be any of cardiac output,cardiac power output, native cardiac output, native cardiac poweroutput, cardiac contractility, cardiac relaxation, fluid responsiveness,volume status, cardiac unloading index, cardiac recovery index,left-ventricular diastolic function, left-ventricular diastolicelastance, left-ventricular systolic elastance, stroke volume, heartrate variability, stroke volume variability, pulse pressure variability,aortic compliance, vascular compliance, or vascular resistance, orsimilar parameters associated with right-side support. These heartfunction parameters can be calculated from the calculated cardiacparameters and other available measured parameters. The heart functionparameters offer additional information to clinicians about the heartfunction and about the balance of the support being provided by thefirst blood pump and the second blood pump. In some implementations, theheart function parameter is also recorded in the memory in order toprovide historical data and heart function parameter trends with respectto time. In some implementations, more than one heart function parameteris determined.

In step 1216, a recommended change to the level of support provided bythe first blood pump and/or the second blood pump is determined. Therecommended change to the level of support may be accessed in a look-uptable stored in the memory, or may be calculated based on current orhistorical values of the cardiac parameters and heart functionparameters. The recommended change to the level of support may include aprompt to increase or decrease pump support, and/or may include arecommendation of an amount of change to be made to the pump support.

In step 1218, the recommended change to the level of support provided bythe first blood pump and/or the second blood pump is generated fordisplay and is displayed. The recommended change to the level of supportprovided by the first blood pump and/or the second blood pump can bedisplayed in the user interface of FIG. 3. In some implementations, therecommended change to the level of support provided by the first bloodpump and/or the second blood pump is displayed on the main screen. Insome implementations, the recommended change to the level of supportprovided by the first blood pump and/or the second blood pump isdisplayed as a pop-up or warning. The recommended change to the level ofsupport provided by the first blood pump and/or the second blood pumpmay be displayed to a clinician with additional information about thefirst and second blood pumps, and with prompts to follow protocols andconduct further checks before changing the level of support provided byadjustment of the motor speed of the first blood pump or the secondblood pump. In some implementations, the controller may determine theappropriate change in motor speed to one or both of the first blood pumpand the second blood pump, and may also determine if the first bloodpump and the second blood pump currently providing support are theoptimal blood pumps to operate at a recommended motor speed to providethe recommended level of support.

Using the data collected by the one or more blood pumps and blood pumpsystems to calculate clinically relevant cardiac parameters and heartfunction parameters and displaying the parameters to clinicians inreal-time provides clinicians with important information about cardiachealth and function that can be used to make clinical decisions aboutsupport. Further, algorithms within the blood pump controller or consolewhich aid clinicians in determining potential issues and providerecommendations to improve cardiac function give clinicians the abilityto detect issues earlier and to respond to problems more quickly thanthey can without this important information.

FIG. 13 shows a block diagram 1300 of a process for automaticallymodifying the level of support provided by a blood pump. In step 1302 ablood pump positioned in the heart is operated to provide a level ofcardiac support to the heart. The blood pump has a cannula and a motoroperating at a motor speed and drawing a variable current to provide thesupport to the heart. At step 1304, a controller coupled to the bloodpump measures the aortic pressure in the heart. At step 1306, thecontroller measures the motor current and the motor speed. At step 1308,the controller determines a pressure gradient across the cannulaassociated with the motor current and the motor speed.

At step 1310, a processor calculates a calculated cardiac parameterbased on the aortic pressure and the pressure gradient across thecannula associated with the motor current and the motor speed. At step1312, the calculated cardiac parameter is recorded in a memory. At step1314, a heart function parameter is determined based on the calculatedcardiac parameter. In some implementations, the heart function parameteris also stored in the memory. At step 1316, a recommended change to thelevel of cardiac support support provided by the blood pump isdetermined based on at least one of the calculated cardiac parameter andthe heart function parameters. At step 1318, the recommended change tothe level of cardiac support is generated for display.

In some implementations, more than one cardiac parameter is calculatedfrom the aortic pressure and the pressure gradient across the cannula.For example, any number of cardiac parameters can be calculated,including LVEDP, LVP, aortic pulse pressure, mean aortic pressure, pumpflow, pressure gradient, or heart rate. In some implementations, thesecardiac parameters are also generated for display as maximum or minimumvalues, average values, instantaneous values, historical trends, orwaveforms. In some implementations, more than one heart functionparameter is determined from the cardiac parameters. For example, theheart function parameter may be a cardiac output, cardiac power output,native cardiac output, native cardiac power output, cardiaccontractility, cardiac relaxation, fluid responsiveness, volume status,cardiac unloading index, cardiac recovery index, left-ventriculardiastolic function, left-ventricular diastolic elastance,left-ventricular systolic elastance, stroke volume, heart ratevariability, stroke volume variability, pulse pressure variability,aortic compliance, vascular compliance, or vascular resistance.

In some implementations, the calculated cardiac parameter is a LVEDP andthe heart function parameter is a cardiac power output. By calculatingthe LVEDP and cardiac power output, a recommendation for modulation ofcardiac support can be determined based on historical data. Based on thepatient cardiac health as illustrated by the LCEDP and cardiac poweroutput, a recommendation to increase the motor speed (to provideincreased cardiac support by the blood pump for patients with failinghealth) or to decrease the motor speed (to wean a patient with improvinghealth from the blood pump) may be determined, generated for display,and displayed to a health care professional.

Such recommendations may be determined by comparing a current value ofthe LVEDP and/or cardiac power output to a previous value or to a setthreshold value. Based on the comparison, a look up table stored in thememory may provide a recommendation which can include an indication ofthe determined recommended change in support level, as well as a list ofsteps to achieve the recommended change. Alternatively, in someimplementations, the recommended change in the level of cardiac supportcan be automated by the controller.

Various combinations of cardiac metrics and parameters can be useful indetermining aspects of patient cardiac health and functioning of boththe heart and the blood pump. The values of these parameters, as well asrecommendations and warnings generated by the algorithms based onhistorical information or present thresholds based on patient health,enable health care professionals to make informed decisions aboutmodulation of support, as well as a number of other healthcare decisionsas described above in reference to FIGS. 4-12.

FIG. 14 shows a block diagram of an exemplary blood pump system 1400 toenact any of the methods described above with regard to FIGS. 4-13. Theheart pump system 1400 may operate within a heart, partially within theheart, outside the heart, partially outside the heart, partially outsidethe vascular system, or in any other suitable location in a patient'svascular system. The blood pump system 1400 includes a console 1401 anda blood pump 1402. The console 1401 includes a drive unit 1404, a memory1406, a processor 1408, circuitry 1403, and a display 1410.

The blood pump system 1400 may be used with any suitable blood pumpdevice, for example, blood pump 1402 may be blood pump 100 shown in FIG.1, to provide cardiac support to the right or left side of the heart.The blood pump 1402 includes motor 1405 and sensor 1407, as well asother components of blood pump 100 in FIG. 1, which are not shown. Insome implementations, the blood pump system 1400 may be used with twoblood pumps in order to provide cardiac support to the left and rightsides of the heart simultaneously.

The blood pump 1402 is coupled to the drive unit 1404 by circuitry 1403.All or part of the circuitry 1403 may be in the console 1401separate/remote from the blood pump 1402. In some implementations, thecircuitry 1403 is internal to the blood pump 1402. The circuitry 1403and the blood pump 1402 are not shown to scale. The drive unit 1404supplies a current to the motor 1405 of the heart pump 1402 by circuitry1403. The current that the drive unit 1404 supplies to the motor 1405 ofthe heart pump 1402 over wire 1426 is measured by the current sensor1409 in or coupled to the drive unit 1404.

The placement signal or aortic pressure is measured at the pressuresensor 1407 located on the blood pump 1402. The pressure detected at thepressure sensor 1307 is received through circuitry 1403 at the driveunit 1404 and may be passed to the processor 1408 along with the currentsupplied to the motor 1405. In some implementations, the aortic pressuremay be measured by a pressure sensor 1407 coupled to the blood pump1402, by a separate catheter, by a noninvasive pressure sensor, or byany other suitable sensor. The pressure sensor 1407 may be afluid-filled tube, a differential pressure sensor, hydraulic sensor,piezo-resistive strain gauge, optical interferometry sensor or otheroptical sensor, MEMS piezo-electric sensor, or any other suitablesensor.

The processor 1408 includes software and/or hardware allowing it toreceive the motor current and pressure measurements from the drive unit1404 and use the values to determine a plurality of additional cardiacparameters and heart function parameters. For example, the processorincludes software that uses the methods described with regard to FIGS.2A-2E to calculate a LVP and LVEDP from the motor current of the bloodpump 1402 and aortic pressure information received from the pressuresensor 1407. Further, the processor 1408 is capable of storing receivedmeasurements, the parameters and the values in the memory 1406, and ofaccessing stored values and parameters in the memory for to generate fordisplay on the display 1410.

The processor 1408 further includes algorithms that execute the stepsdescribed with regard to FIGS. 4-13 to accept or request values of thecurrent and aortic pressure form the drive unit 1404 and determine fromthese values cardiac and heart function parameters indicative of ahealth or function of a heart. The values can also be generated fordisplay to a user and be displayed on the display 1410.

The processor 1408 is capable of accessing functions and look-up tablesstored in the memory 1406 in order to make determinations regarding thecalculated cardiac and heart function parameters and to use thedeterminations to make recommendations regarding the treatment andsupport provided to a patient's heart. The processor 1408 is capable ofgenerating the recommendations and displaying these recommendations ondisplay 1410.

Display 1410 may be substantially similar to the user interface 300 inFIG. 3. The display provides the calculated cardiac parameters and heartfunction parameters of clinical relevance to clinicians to enable themto make treatment decisions with real-time data. Further, the display1410 allows the processor 1408 to display recommendations to a clinicianto allow clinicians to more quickly detect and respond tolife-threatening cardiac issues. The processor 1408 on console 1401 usesthe blood pump 1402 and accessible measurements to provide additionalinformation to clinicians to help them to provide more efficient andmore effective cardiac therapies to patients.

The foregoing is merely illustrative of the principles of thedisclosure, and the apparatuses can be practiced by other than thedescribed embodiments, which are presented for purposes of illustrationand not of limitation. It is to be understood that the apparatusesdisclosed herein, while shown for use in percutaneous insertion of heartpumps, may be applied to apparatuses in other applications.

Variations and modifications will occur to those of skill in the artafter reviewing this disclosure. The disclosed features may beimplemented, in any combination and subcombination (including multipledependent combinations and subcombinations), with one or more otherfeatures described herein. The various features described or illustratedabove, including any components thereof, may be combined or integratedin other systems. Moreover, certain features may be omitted or notimplemented.

In general, embodiments of the subject matter and the functionaloperations described in this specification can be implemented in digitalelectronic circuitry, or in computer software, firmware, or hardware,including the structures disclosed in this specification and theirstructural equivalents, or in combinations of one or more of them.Embodiments of the subject matter described in this specification can beimplemented as one or more computer program products, i.e., one or moremodules of computer program instructions encoded on a computer readablemedium for execution by, or to control the operation of, data processingapparatus. The computer readable medium can be a machine-readablestorage device, a machine-readable storage substrate, a memory device, acomposition of matter affecting a machine-readable propagated signal, ora combination of one or more of them. The term “data processingapparatus” encompasses all apparatus, devices, and machines forprocessing data, including by way of example a programmable processor, acomputer, or multiple processors or computers. The apparatus caninclude, in addition to hardware, code that creates an executionenvironment for the computer program in question, e.g., code thatconstitutes processor firmware, a protocol stack, a database managementsystem, an operating system, or a combination of one or more of them. Apropagated signal is an artificially generated signal, e.g., amachine-generated electrical, optical, or electromagnetic signal that isgenerated to encode information for transmission to suitable receiverapparatus.

A computer program (also known as a program, software, softwareapplication, script, or code) can be written in any form of programminglanguage, including compiled or interpreted languages, and it can bedeployed in any form, including as a stand-alone program or as a module,component, subroutine, or other unit suitable for use in a computingenvironment. A computer program does not necessarily correspond to afile in a file system. A program can be stored in a portion of a filethat holds other programs or data (e.g., one or more scripts stored in amarkup language document), in a single file dedicated to the program inquestion, or in multiple coordinated files (e.g., files that store oneor more modules, sub programs, or portions of code). A computer programcan be deployed to be executed on one computer or on multiple computersthat are located at one site or distributed across multiple sites andinterconnected by a communication network.

The processes and logic flows described in this specification can beperformed by one or more programmable processors executing one or morecomputer programs to perform functions by operating on input data andgenerating output. The processes and logic flows can also be performedby, and apparatus can be implemented as, special purpose logiccircuitry, e.g., an FPGA (field programmable gate array) or an ASIC(application specific integrated circuit).

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read only memory ora random access memory or both. The essential elements of a computer area processor for performing instructions and one or more memory devicesfor storing instructions and data. Generally, a computer will alsoinclude, or be operatively coupled to receive data from or transfer datato, or both, one or more mass storage devices for storing data, e.g.,magnetic, magneto optical disks, or optical disks. However, a computerneed not have such devices.

Examples of changes, substitutions, and alterations are ascertainable byone skilled in the art and could be made without departing from thescope of the information disclosed herein. All references cited hereinare incorporated by reference in their entirety and made part of thisapplication.

We claim:
 1. A method for providing cardiac support to a heart,comprising: operating a blood pump positioned in the heart, the bloodpump having a cannula and including a motor operating at a motor speedand drawing a variable motor current to provide a level of cardiacsupport to the heart; measuring at a controller coupled to the bloodpump, an aortic pressure; measuring, at the controller, the motorcurrent and the motor speed; determining a pressure gradient across thecannula associated with the motor current and the motor speed; using aprocessor to calculate, from the aortic pressure and the pressuregradient across the cannula associated with the motor current and themotor speed, a calculated cardiac parameter; recording, in a memory, thecalculated cardiac parameter; determining, based on the calculatedcardiac parameter, a heart function parameter; determining, based on atleast one of the calculated cardiac parameter and the heart functionparameter, a recommended change to the level of cardiac support providedby the blood pump; generating for display the recommended change.
 2. Themethod of claim 1, the method further comprising: accepting a user inputin response to the displayed recommended change to the level of cardiacsupport provided by the blood pump; and adjusting the motor speed toadjust the level of cardiac support according to the user input.
 3. Themethod of claim 2, wherein adjusting the motor speed according to theuser input comprises increasing the motor speed to increase the flow ofblood from the heart.
 4. The method of claim 2, wherein adjusting themotor speed according to the user input comprises decreasing the motorspeed to wean the heart from the cardiac support.
 5. The method of claim2, wherein the calculated cardiac parameter is at least one of aleft-ventricular pressure, a left ventricular end diastolic pressure, anaortic pulse pressure, and a mean aortic pressure.
 6. The method ofclaim 5, wherein the heart function parameter is selected from a cardiacoutput and a cardiac power output.
 7. The method of claim 6, the methodfurther comprising accessing, in the memory, a history of previouslyrecorded cardiac parameters and heart function parameters.
 8. The methodof claim 7, the method further comprising generating for display atleast one of the calculated cardiac parameter and the heart functionparameter as a function of time.
 9. The method of claim 8, wherein thedetermined recommended change to the motor speed is based on the historyof at least one of the previously recorded cardiac parameters and heartfunction parameters.
 10. The method of claim 9, wherein determining arecommended change in support further comprises: determining a change inone of the calculated cardiac parameter or the heart function parameterbased on the history of previously recorded cardiac parameters and heartfunction parameters; determining a recommended alteration in theprovided level of cardiac support based on the change; and convertingthe recommended alteration in provided level of cardiac support to arecommended change in motor speed.
 11. The method of claim 1, the methodfurther comprising: determining, based on at least one of the calculatedcardiac parameter and the heart function parameter, a suction event atan inflow of the blood pump; and generating for display a warning of asuction event.
 12. The method of claim 11, the method furthercomprising: identifying, based on at least one of the calculated cardiacparameter and the heart function parameter, a cause of the suctionevent; and generating for display a recommendation to address the causeof the suction event.
 13. The method of claim 12, wherein identifyingthe cause of the suction event comprises: comparing a value of thecalculated cardiac parameter to a threshold value, wherein the cardiacparameter is a left ventricular pressure and the threshold is zero; andcomparing a value of the left ventricular pressure over a cardiac cycleto a value of the aortic pressure over a cardiac cycle.
 14. The methodof claim 13, wherein the method further comprises: identifying adiastolic suction event if a minimum value of the left ventricularpressure is less than the threshold in a diastole phase but normal insystolic phase of the cardiac cycle.
 15. The method of claim 13, whereinthe method further comprises: identifying a systolic suction event if aminimum value of the left ventricular pressure is less than thethreshold in the diastolic phase, and a value of the left ventricularpressure does not exceed a value of the aortic pressure over the cardiaccycle.
 16. A percutaneous blood pump system comprising: a blood pumpconfigured to be positioned in a heart, the blood pump comprising: acannula; a sensor configured to measure an aortic pressure in thehearth; and a motor operable at a motor speed and configured to draw avariable motor current to provide a level of cardiac support to theheart; a controller configured to control the motor current and motorspeed, the controller comprising: a memory; a user interface; and aprocessor configured to: measure the motor current and the motor speedof the motor; receive an indication of the aortic pressure from thesensor and convert the indication of the aortic pressure to an aorticpressure measurement; determine a pressure gradient across the cannulaassociated with the motor current and the motor speed; calculate atleast one cardiac parameter based on the aortic pressure measurement andthe pressure gradient across the cannula; record the at least onecalculated cardiac parameter in the memory; calculate, based on the atleast one cardiac parameter, one or more heart function parameters;determine, based on at least one of the at least one cardiac parameterand the one or more heart function parameters, a recommended change tothe level of cardiac support to the heart; and generate for display onthe user interface the recommended change to the level of cardiacsupport.
 17. The blood pump system of claim 16, wherein the processor isfurther configured to calculate a left ventricular pressure as a cardiacparameter and a cardiac power output as a heart function parameter. 18.The blood pump system of claim 17, wherein the processor is furtherconfigured to: record the at least one calculated cardiac parameter inthe memory as a first calculated cardiac parameter; and record a secondcalculate cardiac parameter in the memory at a later time.
 19. The bloodpump system of claim 18, the processor further configured to: access thefirst cardiac parameter and the second cardiac parameter in the memory;and determine a recommended change to the motor speed based on acompared value of the first cardiac parameter to the second cardiacparameter.
 20. The blood pump system of claim 16, the processor furtherconfigured to: determine, based on at least one of the calculatedcardiac parameter and the heart function parameter, a suction event atan inflow of the blood pump; and generate a warning of a suction eventfor display on the user interface.